Publications

  • S. Kumar, L. R. Maurer, G. Schnakenburg, U. Das, A. C. Filippou
    NHC-Supported 2-Sila and 2-Germavinylidenes: Synthesis, Dynamics, First Reactivity and Theoretical Studies
    Angew. Chem. Int. Ed. 2024, e202400227.
    DOI: 10.1002/anie.202400227
  • L. R. Maurer, J. Rump, A. C. Filippou
    The Electronic Nature of Cationic Group 10 Ylidyne Complexes
    Inorganics 2023, 11, 3, 129.
    DOI: 10.3390/inorganics11030129
  • S. Karwasara, L. R. Maurer, B. Peerless, G. Schnakenburg, U. Das, A. C. Filippou
    (NHC)Si═C═N–R: A Two-Coordinated Si0-Isocyanide Compound as Si(NHC) Transfer Reagent
    J. Am. Chem. Soc. 2021, 143, 36, 14780–14794.
    DOI: 10.1021/jacs.1c06628
  • P. Ghana, J. Rump, G. Schnakenburg, M. I. Arz, A. C. Filippou
    Planar Tetracoordinated Silicon (ptSi): Room-Temperature Stable Compounds Containing Anti-van’t Hoff/Le Bel Silicon
    J. Am. Chem. Soc. 2021, 143, 1, 420–432.
    DOI: 10.1021/jacs.0c11628
  • P. Ghana, M. I. Arz, U. Chakraborty, G. Schnakenburg, A. C. Filippou
    Linearly Two-Coordinated Silicon: Transition Metal Complexes with the Functional Groups M≡Si–M and M=Si=M
    J. Amer. Chem. Soc. 2018, 140, 7187-7198.
    DOI: 10.1021/jacs.8b02902
  • N. Fleck, G. Schnakenburg, A. C. Filippou, O. Schiemann
    Tris[2,2,6,6-tetramethyl-8-(trimethylsilyl)benzo[1,2-d;4,5-d']bis(1,3-dithiol)-4-yl]methanol diethyl ether monosolvate
    Acta Cryst. 2018, E74, 539-542.
    DOI: 10.1107/S2056989018004516
  • P. Ghana, M. Arz, G. Schnakenburg, M. Straßmann, A. C. Filippou
    Metal-Silicon Triple Bonds: Facile Access to the [Si(η5-Cp*)]+ Cation and its Conversion to the Silylidyne Complex [TpMe(CO)2MoSi(η3-Cp*)]
    Organometallics 2018, 37, 772-780.
    DOI: 10.1021/acs.organomet.7b00665
  • A. C. Filippou, D. Hoffmann, G. Schnakenburg
    Triple Bonds of Niobium with Silicon, Germanium and Tin: The Tetrylidyne Complexes [(κ3-tmps)(CO)2Nb≡E–R] (E = Si, Ge, Sn; tmps = MeSi(CH2PMe2)3; R = aryl)
    Chem. Sci. 2017, 8, 6290-6299.
    DOI: 10.1039/c7sc02708g
  • B. Wezisla, J. Lindner, U. Das, A. C. Filippou, P. Vöhringer
    The Femtochemistry of a Ferracyclobutadiene
    Angew. Chem. 2017, 129, 7005-7009; Angew. Chem. Int. Ed. 2017, 56, 6901-6905.
    DOI: 10.1002/anie.201702987
  • Y. Lebedev, U. Das, G. Schnakenburg, A. C. Filippou
    Coordination Chemistry of E(Idipp)]2+ Ligands (E = Ge, Sn): Metal Germylidyne [Cp*(CO)2WGe(Idipp)]+ and Metallotetrylene [Cp*(CO)3W-Ge(Idipp)]+ Cations
    Organometallics 2017, 36, 1530-1540.
    DOI: 10.1021/acs.organomet.7b00110
  • M. I. Arz, D. Hoffmann, G. Schnakenburg, A. C. Filippou
    NHC-stabilized SiII Halides: Reactivity Studies with Diazoalkanes and Azides
    Z. Anorg. Allg. Chem. 2016, 642 (22), 1287-1294.
    DOI: 10.1002/zaac.201600286
  • M. I. Arz, G. Schnakenburg, A. Meyer, O. Schiemann, A. C. Filippou
    The Si2H radical supported by two N-heterocyclic carbenes
    Chem. Sci. 2016, 7, 4973-4979.
    DOI: 10.1039/c6sc01569g
  • M. I. Arz, M. Straßmann, D. Geiß, G. Schnakenburg, A. C. Filippou
    Addition of Small Electrophiles to N-Heterocyclic-Carbene-Stabilized Disilicon(0): A Revisit of the Isolobal Concept in Low-valent Silicon Chemistry
    J. Amer. Chem. Soc. 2016, 138, 4589-4600.
    DOI: 10.1021/jacs.6b01018
  • J. Torres-Alacan, U. Das, Boris Wezisla, M. Straßmann, A. C. Filippou, P. Vöhringer
    Photochemistry of a Puckered Ferracyclobutadiene in Liquid Solution Studied by TimeResolved Fourier-Transform Infrared Spectroscopy
    Chem. Eur. J. 2015, 21, 17184-17190.
    DOI: 10.1002/chem.201503300
  • M. I. Arz, D. Geiß, M. Straßmann, G. Schnakenburg, A. C. Filippou;
    Silicon(I) Chemistry: The NHC-stabilised silicon(I) halides Si2X2(Idipp)2 (X = Br, I) and the disilicon(I)-iodido cation [Si2I(Idipp)2]+;
    Chem. Sci. 2015, 6, 6515 – 6524.
    DOI: 10.1039/c5sc02681d
  • P. Ghana, M. I. Arz, U. Das, G. Schnakenburg, A. C. Filippou
    Si=Si Double Bonds: Synthesis of an NHC-Stabilized Disilavinylidene
    Angew. Chem. 2015, 127, 10118-10123; Angew. Chem. Int. Ed. 2015, 54, 9980-9985.
    DOI: 10.1002/ange.201504494
  • M. I. Arz, M. Straßmann, A. Meyer, G. Schnakenburg, O. Schiemann, A. C. Filippou
    One-Electron Oxidation of a Disilicon(0) Compound: An Experimental and Theoretical Study of [Si2]+ Trapped by N-Heterocyclic Carbenes
    Chem. Eur. J. 2015, 21, 12509-12516.
    DOI: 10.1002/chem.201502199
  • D. Geiß, M. I. Arz, M. Straßmann, G. Schnakenburg, A. C. Filippou
    Si=P double bonds: Experimental and Theoretical Study of a NHC-Stabilized Phosphasilenylidene
    Angew. Chem. 2015, 127, 2777-2782; Angew. Chem. Int. Ed. 2015, 54, 2739-2744.
    DOI: 10.1002/ange.201411264
  • A. C. Filippou
    Friedrich August Kekulé und „das Alte Chemische Institut“ in Bonn, Historische Stätten der Chemie
    Herausgeber: Gesellschaft Deutscher Chemiker, ISBN: 978-3-936028-82-9, 2014.
  • Y. N. Lebedev, U. Das, O. Chernov, G. Schnakenburg, A. C. Filippou
    [2+2+1] Cycloadditions of Bis(dialkylamino)acetylenes with SiI2(Idip): Syntheses and Reactivity Studies of Unprecedented 2,3,4,5-Tetraamino-1H-siloles
    Chem. Eur. J. 2014, 20, 9280-9289.
    DOI: 10.1002/chem.201403108
  • A. C. Filippou, B. Baars, O. Chernov, Y. N. Lebedev, G. Schnakenburg
    Silicon-Oxygen Double Bonds: A Stable Silanone with a Trigonal-planar Coordinated Silicon Center
    Angew. Chem. 2014, 126, 576-581; Angew. Chem. Int. Ed. 2014, 53, 565-570.
    DOI: 10.1002/anie.201308433
  • J. T. Alacan, U. Das, A. C. Filippou, P. Vöhringer
    Observing the Formation and the Reactivity of an Octahedral Nitridoiron(V) complex in Real Time
    Angew. Chem. 2013, 125, 13067–13071; Angew. Chem. Int. Ed. 2013, 52, 12833-12837.
    DOI: 10.1002/anie.201306621
  • A. C. Filippou, P. Ghana, U. Chakraborty, G. Schnakenburg
    Manganese-Tin Triple Bonds: A New Synthetic Route to the Manganese Stannylidyne Complex Cation trans-[H(dmpe)2Mn≡Sn(C6H3-2,6-Mes2)]+ (dmpe = Me2PCH2-CH2PMe2, Mes = 2,4,6-Trimethylphenyl)
    J. Am. Chem. Soc. 2013, 135, 11525-11528.
    DOI: 10.1021/ja406290t
  • B. Askevold, A. Friedrich, M. R. Buchner, B. Lewall, A. C. Filippou, E. Herdtweck, S. Schneider
    Reactivity of Iridium(I) PNP amido complexes toward protonation and oxidation
    J. Organomet. Chem. 2013, 744, 35-40.
    DOI: 10.1016/j.jorganchem.2013.04.022
  • A. C. Filippou, Y. N. Lebedev, O. Chernov, M. Straßmann, G. Schnakenburg
    Silicon(II) Coordination Chemistry: N-Heterocyclic Carbene complexes of Si2+ and SiI+
    Angew. Chem. 2013, 125, 7112–7116; Angew. Chem. Int. Ed. 2013, 52, 6974-6978.
    DOI: 10.1002/ange.201301363
  • A. C. Filippou, U. Chakraborty, G. Schnakenburg
    Rhenium-Germanium Triple Bonds: Syntheses and Reactions of the Germylidyne Complexes mer-[X2(PMe3)3Re≡Ge-R], (X = Cl, I, H; R = m-terphenyl)
    Chem. Eur. J. 2013, 19, 5676-5686.
    DOI: 10.1002/chem.201300017
  • E. Niecke, A. C. Filippou
    Rolf Appel (1921 – 2012)
    Angew. Chem. 2012, 124, 9350; Angew. Chem. Int. Ed. 2012, 51, 9216.
    DOI: 10.1002/anie.201205250
  • A. C. Filippou, E. Niecke
    Rolf Appel (1921 – 2012)
    Nachrichten aus der Chemie 2012, 60, 579.
  • H.Vennekate, D. Schwarzer, J. T. Alacan, Oliver Krahe, A. C. Filippou, F. Neese, P. Vöhringer
    Ultrafast primary processes of an iron-(III) azido complex in solution induced with 266 nm light
    Phys. Chem. Chem. Phys. 2012, 14, 6165–6172.
    DOI: 10.1039/C2CP23435A
  • J. T. Alacan, O. Krahe, A. C. Filippou, F. Neese, D. Schwarzer, P. Vöhringer
    The photochemistry of [FeIIIN3(cyclam-ac)]PF6 at 266 nm
    Chem. Eur. J. 2012, 18, 3043–3055.
    DOI: 10.1002/chem.201103294
  • A. C. Filippou, K. W. Stumpf, O. Chernov, G. Schnakenburg
    Metal Activation of a Germylenoid, a New Approach to Metal-Germanium Triple Bonds: Synthesis and Reactions of the Germylidyne Complexes [Cp(CO)2M≡Ge–C(SiMe3)3] (M = Mo, W)
    Organometallics 2012, 31, 748-755.
    DOI: 10.1021/om201176n
  • A. C. Filippou, A. Barandov, G. Schnakenburg, B. Lewall, M. van Gastel, A. Marchanka
    Open Shell Complexes Containing Metal-Germanium Triple Bonds
    Angew. Chem. 2012, 124, 813-817; Angew. Chem. Int. Ed. 2012, 51, 789-793.
    DOI: 10.1002/anie.201107120
  • A. C. Filippou, O. Chernov, G. Schnakenburg
    Chromium-Silicon Multiple Bonds: The Chemistry of Terminal N-HeterocyclicCarbene-Stabilized Halosilylidyne Ligands
    Chem. Eur. J. 2011, 17, 13574-13583.
    DOI: 10.1002/chem.201102659
  • A. C. Filippou, O. Chernov, G. Schnakenburg
    Metal-Silicon Triple Bonds: Nucleophilic Addition and Redox Reactions of the Silylidyne Complex [Cp(CO)2Mo≡Si-R]
    Angew. Chem. 2011, 123, 1154-1158; Angew. Chem. Int. Ed. 2011, 50, 1122-1126.
    DOI: 10.1002/anie.201005794
  • P. Portius, A. C. Filippou, G. Schnakenburg, M. Davis, K.-D. Wehrstedt
    Neutral LewisBase Adducts of Silicon Tetraazide
    Angew. Chem. 2010, 122, 8185-8189; Angew. Chem. Int. Ed. 2010, 49, 8013-8016.
    DOI: 10.1002/anie.201001826
  • A. C. Filippou, O. Chernov, K. W. Stumpf, G. Schnakenburg
    Metal-Silicon Triple Bonds: The Molybdenum Silylidyne Complex [Cp(CO)2Mo≡Si-R]
    Angew. Chem. 2010, 122, 3368-3372; Angew. Chem. Int. Ed. 2010, 49, 3296-3300.
    DOI: 10.1002/anie.201000837
  • A. C. Filippou, O. Chernov, B. Blom, K. W. Stumpf, G. Schnakenburg
    Stable N-Heterocyclic Carbene Adducts of Arylchlorosilylenes and their Germanium Homologues
    Chem. Eur. J. 2010, 16, 2866-2872.
    DOI: 10.1002/chem.200903019
  • A. C. Filippou, Buch-Rezension
    Landmarks in Organo-Transition Metal Chemistry- A Personal View, (Autor: H. Werner)
    Angew. Chem. 2009, 121, 7613-7614; Angew. Chem. Int. Ed. 2009, 48, 7477-7478.
    DOI: 10.1002/anie.200903542
  • A. C. Filippou, O. Chernov, G. Schnakenburg
    SiBr2(Idipp): A Stable N-Heterocyclic Carbene Adduct of SiBr2
    Angew. Chem. 2009, 121, 5797-5800; Angew. Chem. Int. Ed. 2009, 48, 5687-5690.
    DOI: 10.1002/anie.200902431
  • N. Weidemann, G. Schnakenburg, A.C. Filippou
    Neuartige Silane mit sterisch anspruchsvollen Aryl-Substituenten
    Z. Anorg. Allg. Chem. 2009, 635, 253-259.
    DOI: 10.1002/zaac.200800420
  • H. Rohde, M. Menzel, F. Renz, A.C. Filippou
    Investigation of Mo- and W-stannylidyne Complexes by Mössbauer spectroscopy
    Hyperfine Interactions 2008, 185, 129-132.
    DOI: 10.1007/s10751-008-9821-7
  • A. C. Filippou, N. Weidemann, G. Schnakenburg
    Tungsten-Mediated Activation of a Pb(II)-N bond: A New Route to Tungsten-Lead Triple Bonds
    Angew. Chem. 2008, 120, 5883-5886; Angew. Chem. Int. Ed. 2008, 47, 5799-5802.
    DOI: 10.1002/anie.200801331
  • A. C. Filippou, N.Weidemann, A. I. Philippopoulos, G. Schnakenburg
    Activation of Arylgermanium(II) Chlorides by [Mo(PMe3)6] and [W(η2-CH2PMe2)H(PMe3)4]: A New Route to Metal-Germanium Triple Bonds
    Angew. Chem. 2006, 118, 6133-6137; Angew. Chem. Int. Ed. 2006, 45, 5987-5991.
    DOI: 10.1002/ange.200602061
  • N. G. Tsierkezos, A. C. Filippou
    Thermodynamic investigation of N,N-dimethylformamide/toluene binary mixtures in the temperature range from 278.15 K to 293.15 K
    J. of Chem. Thermodynamics, 2006, 38, 952-961.
    DOI: 10.1016/j.jct.2005.10.008
  • A. C. Filippou, G. Schnakenburg, A. I. Philippopoulos, N. Weidemann
    Ge2 Trapped by Triple bonds between two Metal Centers: The Germylidyne Complexes trans,trans-[Cl(depe)2M≡Ge-Ge≡M(depe)2Cl] (M = Mo, W) and Bonding Analyses of the M≡Ge-Ge≡M chain
    Angew. Chem. 2005, 117, 6133-6139; Angew. Chem. Int. Ed. 2005, 44, 5979-5985.
    DOI: 10.1002/anie.200501968
  • N. G. Tsierkezos, I. E. Molinou, A. C. Filippou
    Thermodynamic Properties of Binary Mixtures of Cyclohexanone with n-Alkanols (C1-C5) at 293.15 K
    Journal of Solution Chem. 2005, 34, 1371-1386.
    DOI: 10.1007/s10953-005-8508-9
  • A. C. Filippou, N. Weidemann, G. Schnakenburg, H. Rohde, A. I. Philippopoulos
    Tungsten-Lead Triple Bonds: Syntheses, Structures and Coordination Chemistry of the Plumbylidyne Complexes trans-[X(PMe3)4W≡Pb-C6H3-2,6-Trip2] (X = Br, I; Trip = C6H2-2,4,6-iPr3)
    Angew. Chem. 2004, 116, 6674-6678; Angew. Chem. Int. Ed. 2004, 43, 6512-6516.
    DOI: 10.1002/ange.200461725
  • A. C. Filippou, H. Rohde, G. Schnakenburg
    Triple bond to Lead: Synthesis and Characterization of the Plumbylidyne Complex trans-[Br(PMe3)4Mo≡Pb-C6H3-2,6-Trip2]
    Angew. Chem. 2004, 116, 2293-2297; Angew. Chem. Int. Ed. 2004, 43, 2243-2247.
    DOI: 10.1002/anie.200353477
  • A. C. Filippou, A. I. Philippopoulos, P. Portius, G. Schnakenburg
    Halide Substitution Reactions of the Germylidyne Complexes trans-[X(dppe)2W≡Ge-(η1-Cp*)] (X = Cl, I; dppe = Ph2PCH2CH2PPh2; Cp* = C5Me5)
    Organometallics 2004, 23, 4503-4512.
    DOI: 10.1021/om049625m
  • A. C. Filippou, S. Schneider, G. Schnakenburg
    [Na(THF)2Cr(N3N)]: The First Trigonal Monopyramidal Chromium(II) Complex
    Inorg. Chem. 2003, 42, 6974-6976.
    DOI: 10.1021/ic0349961
  • A. C. Filippou, S. Schneider, G. Schnakenburg
    A Pair of Remarkably Stable Mononuclear Chromium(III) and Chromium(IV) Hydrides
    Angew. Chem. 2003, 115, 4624-4627; Angew. Chem. Int. Ed. 2003, 42, 4486-4489.
    DOI: 10.1002/ange.200352177
  • A. C. Filippou, S. Schneider
    Metallorganische Chemie des Chroms in ungewöhnlichen Oxidationsstufen und Koordinationsgeometrien - Modellverbindungen für Heterogenkatalysatoren der OlefinPolymerisation
    Humboldt-Spektrum 2003, 2-3, 36-40.
  • A. C. Filippou, A. I. Philippopoulos, G. Schnakenburg
    Triple-Bonding to Tin: Synthesis and Characterization of the Square-Pyramidal Stannylyne Complex Cation [(dppe)2W≡Sn-C6H3-2,6-Mes2]+ (dppe = Ph2PCH2CH2PPh2; Mes = C6H2-2,4,6-Me3);
    Organometallics 2003, 22, 3339-3341.
    DOI: 10.1021/om030303c
  • A. C. Filippou, G. Schnakenburg, A. I. Philippopoulos
    trans-Dichlorobis[ethane-1,2-diylbis(diphenylphosphine)-κ2P,P']tungsten(II) pentane hemisolvate;
    Acta Cryst. 2003, E59, m602-m604.
    DOI: 10.1107/S1600536803014193
  • A. C. Filippou, S. Schneider
    Unusually Stable Chromium(IV) Alkyls Bearing a Triamidoamine Ligand
    Organometallics 2003, 22, 3010-3012.
    DOI: 10.1021/om030273d
  • A. C. Filippou, T. Rosenauer, G. Schnakenburg
    Selective C-C coupling reactions of Me2N-C≡C-NMe2 at iron(0) centers
    Perspectives in Organometallic Chemistry, C.G. Screttas, B.R. Steele (Eds.), The Royal Society of Chemistry, Cambridge, 2003, 120-135.
    ISBN: 1847551645
  • A. C. Filippou, P. Portius, A. I. Philippopoulos, H. Rohde
    Triple bonding to Tin: Synthesis and Characterization of the Stannylyne complex trans-[Cl(PMe3)4W≡Sn-C6H3-2,6-Mes2] (Mes = C6H2-2,4,6-Me3)
    Angew. Chem. 2003, 115, 461-464; Angew. Chem. Int. Ed. 2003, 42, 445-447.
    DOI: 10.1002/anie.200390135
  • A. I. Philippopoulos, B. Ziemer, A. C. Filippou
    trans-Bis[ethane-1,2-diylbis(diphenylphosphane)-κ2P,P']bis(thiocyanato-κN) molybdenum(II) toluene solvate
    Acta Cryst. 2002, E58, m705-m706.
    DOI: 10.1107/S1600536802020123
  • A. C. Filippou, P. Portius
    Siliciumpolyazide und Verfahren zu ihrer Herstellung
    Patent Anmeldung beim Deutschen Patent- und Markenamt am 31.5.2002, Aktenzeichen: 102 25 175.4.
  • A. C. Filippou, P. Portius, G. Schnakenburg
    The Hexaazidosilicate(IV) ion: Synthesis, properties and molecular structure
    J. Am. Chem. Soc. 2002, 124, 12396-12397.
    DOI: 10.1021/ja0273187
  • A. C. Filippou, S. Schneider, B. Ziemer
    Syntheses and molecular structures of chromium(IV) halides and pseudohalides bearing a triamidoamine ligand
    Eur. J. Inorg. Chem. 2002, 2928-2935.
    DOI: 10.1002/1099-0682(200211)2002:11<2928::AID-EJIC2928>3.0.CO;2-U
  • A. C. Filippou, T. Rosenauer
    A new reaction pathway of Fe(CO)5 with alkynes via ferrabicyclobutenones
    Angew. Chem. 2002, 114, 2499-2502; Angew. Chem. Int. Ed. 2002, 41, 2393-2396.
    DOI: 10.1002/1521-3757(20020703)114:13<2499::AID-ANGE2499>3.0.CO;2-2
  • A. C. Filippou, P. Portius, A. I. Philippopoulos
    Molybdenum and tungsten germylyne complexes of the general formula trans-[X(dppe)2M≡Ge–(η1-Cp*)] (X = Cl, Br, I; dppe = Ph2PCH2CH2PPh2; Cp* = C5Me5): Syntheses, molecular Structures and bonding features of the germylyne ligand
    Organometallics 2002, 21, 653-661.
    DOI: 10.1021/om010785x
  • A. C. Filippou, A. I. Philippopoulos, B. Ziemer
    cis-Dicarbonylbis[1,2-ethanediylbis(diphenylphosphine)-P,P']tungsten(0) benzene sesquisolvate
    Acta Cryst. 2001, E57, m338-m340.
    DOI: 10.1107/S1600536801010893
  • S. Schneider, A. C. Filippou
    Triamidoamine complexes of chromium(III) and chromium(IV)
    Inorg. Chem. 2001, 40, 4674-4677.
    DOI: 10.1021/ic010361v
  • A. C. Filippou, P. Portius, J. G. Winter, G. Kociok-Köhn
    Stereoselective insertion of GeCl2 into tungsten-chlorine Bonds of aminomethylene and aminocarbyne complexes
    J. Organomet. Chem. 2001, 628, 11-24.
    DOI: 10.1016/S0022-328X(01)00748-3
  • A. C. Filippou, P. Portius, C. Jankowski
    Aminomethylene complexes of molybdenum(IV) and tungsten(IV) bearing 1,2-dithiolato ligands
    J. Organomet. Chem. 2001, 617-618, 656-670.
    DOI: 10.1016/S0022-328X(00)00701-4
  • A. C. Filippou, P. Portius, D. U. Neumann, K.-D. Wehrstedt
    Das Hexaazidogermanat(IV)-Ion - Synthese, Strukturen und Reaktionen
    Angew. Chem. 2000, 112, 4524-4527; Angew. Chem. Int. Ed. 2000, 39, 4333-4336.
    DOI: 10.1002/1521-3757(20001201)112:23<4524::AID-ANGE4524>3.0.CO;2-S
  • A. C. Filippou, P. Portius, A. Philippopoulos, G. Kociok-Köhn, B. Ziemer
    Pentane and tetrahydrofurane solvates of trans-dichlorobis[1,2-ethanediylbis(diphenylphosphine)-P,P']molybdenum(II)
    Acta Cryst. 2000, C56, e378-e379.
    DOI: 10.1107/S010827010001060X
  • A. C. Filippou in B. Cornils, W. A. Herrmann, R. Schlögl, C.-H. Wong (Eds.)
    Catalysis from A to Z
    Wiley-VCH Verlag, Weinheim, 2000, S. 2, 51 und 571.
  • A. C. Filippou
    Elektronisch ungesättigte Verbindungen von Hauptgruppenelementen
    Chemie an der Humboldt-Universität zu Berlin, 100 Jahre Chemische Institute in der Hessischen Straße, 2000, 32-37.
  • A. C. Filippou, P. Portius, G. Kociok-Köhn, V. Albrecht
    Oxidation of germanium(II) azides with HN3: A convenient route to hexacoordinate triazidogermanium(IV) compounds
    J. Chem. Soc. Dalton Trans. 2000, 1759-1768.
    DOI: 10.1039/B001198N
  • A. C. Filippou, A. I. Philippopoulos, P. Portius, D. U. Neumann
    Synthese und Struktur der Germylin-Komplexe trans-[X(dppe)2W≡Ge(η1-Cp*)] (X = Cl, Br, I) und Vergleich der W≡E-Bindungen (E = C, Ge) mit Dichtefunktionalrechnungen
    Angew. Chem. 2000, 112, 2881-2884; Angew. Chem. Int. Ed. 2000, 39, 2778-2781.
    DOI: 10.1002/1521-3773(20000804)39:15<2778::AID-ANIE2778>3.0.CO;2-2
  • Á. M. Montana, D. Fernández, R. Pagès, A. C. Filippou, G. Kociok-Köhn
    Enantioselective synthetic methodology to prepare trans-fused bicyclo[5.3.0]decane systems: an approach to the synthesis of the pseudoguaiane carbon framework
    Tetrahedron 2000, 56, 425-439.
    DOI: 10.1016/S0040-4020(99)01009-1
  • A. C. Filippou, B. Lungwitz, G. Kociok-Köhn
    Intramolecular carbyne-isocyanide coupling to an alkyne ligand at a d4 tungsten center
    Eur. J. Inorg. Chem. 1999, 1905-1910.
    DOI: 10.1002/(SICI)1099-0682(199911)1999:11<1905::AID-EJIC1905>3.0.CO;2-W
  • A. C. Filippou, R. Steck, G. Kociok-Köhn
    Triazidogermyl complexes of tungsten: Synthesis, crystal structure and hydrolysis to a metallocyclotrigermoxane
    J. Chem. Soc. Dalton Trans. 1999, 2267-2268.
    DOI: 10.1039/A904628C
  • A. C. Filippou, J. G. Winter, G. Kociok-Köhn, C. Troll and I. Hinz
    Electron-rich trichlorogermyl complexes of molybdenum and tungsten bearing a cyclopentadienyl ligand: Synthesis, crystal structures and cyclic voltammetric studies
    Organometallics 1999, 18, 2649-2659.
    DOI: 10.1021/om990101+
  • G. Kociok-Köhn, J. G. Winter, A. C. Filippou
    Trimethylphosphonium-trichlorogermanate(II)
    Acta Cryst. 1999, C55, 351-353.
    DOI: 10.1107/S010827019801169X
  • M. Haufe, R. D. Köhn, G. Kociok-Köhn, A. C. Filippou
    The chemistry of 1,3,5,-triazacycyclohexane complexes. 7, Synthesis and structure determination of ethyl(1,3,5-tribenzyl(1,3,5-triazacyclohexane))zinc(II)-hexafluorophosphate
    Inorg. Chem. Comm. 1998, 1, 263-266.
    DOI: 10.1016/S1387-7003(98)00074-4
  • A. C. Filippou, P. Portius, G. Kociok-Köhn
    Germanium(II) azids: Synthesis and crystal structure of Tp'GeN3 [Tp' = hydrotris-(3,5-dimethylpyrazol-1-yl)borato];
    J. Chem. Soc. Chem. Commun. 1998, 2327-2328.
    DOI: 10.1039/A807282E
  • J. G. Winter, P. Portius, G. Kociok-Köhn, R. Steck, A. C. Filippou
    Insertion of Cp*GeCl into a tungsten-chlorine bond and crystal structures of the germylenes Cp*GeCl, [Cp*GeBr]2 and [Cp*Ge][BF4] (Cp* = pentamethylcyclopentadienyl)
    Organometallics 1998, 17, 4176-4182.
    DOI: 10.1021/om980425i
  • A. C. Filippou, J. G. Winter, G. Kociok-Köhn, I. Hinz
    Dimetallagermanes of molybdenum and tungsten: synthesis, structures and reactions
    J. Chem. Soc. Dalton Trans. 1998, 2029-2036.
    DOI: 10.1039/A801380B
  • A. C. Filippou, J. G. Winter, M. Feist, G. Kociok-Köhn, I. Hinz
    Trichlorogermyl complexes of molybdenum and tungsten bearing cyclopentadienyl ligands: Synthesis, structure and isomerization studies
    Polyhedron 1998, 17, 1103-1114.
    DOI: 10.1016/S0277-5387(97)00498-1
  • A. C. Filippou
    Metal-centered Coupling Reactions of C1-Ligands analogous to Carbon Monoxide
    in Organic Synthesis via Organometallics, G. Helmchen, J. Dibo, D. Flubacher, B. Wiese (Eds.), OSM 5, Friedr. Vieweg & Sohn Verlagsgesellschaft 1997, 97-119.
  • R. D. Köhn, M. Haufe, G. Kociok-Köhn, A. C. Filippou
    The chemistry of 1,3,5,-Triazacycyclohexane complexes. 6. Synthesis and characterization of the Cobalt(II) methoxide core {Co3(OMe)4}2+
    Inorg. Chem. 1997, 36, 6064-6069.
    DOI: 10.1021/ic9704593
  • A. C. Filippou, J. G. Winter, G. Kociok-Köhn, I. Hinz
    Insertion of GeCl2 into molybdenum-hydrogen bonds: A convenient route to dichlorogermyl complexes
    J. Organomet. Chem. 1997, 544, 225-231.
    DOI: 10.1016/S0022-328X(97)00285-4
  • A. C. Filippou, J. G. Winter, G. Kociok-Köhn, I. Hinz
    Insertion of GeCl2 into Group VI transition metal-chlorine bonds: Synthesis, spectroscopy and structure of molybdenum and tungsten trichlorogermyl complexes
    J. Organomet. Chem. 1997, 542, 35-49.
    DOI: 10.1016/S0022-328X(97)00284-2
  • A. C. Filippou, D. Wössner, G. Kociok-Köhn, I. Hinz
    Metal-carbon multiple bonds: Half-sandwich phenylcarbyne complexes of chromium - synthesis, structure, electrochemistry and reactions with PMe3
    J. Organomet. Chem. 1997, 541, 333-343.
    DOI: 10.1016/S0022-328X(97)00084-3
  • A. C. Filippou, D. Wössner, G. Kociok-Köhn, I. Hinz, L. Grubert
    Metal-carbon multiple bonds: synthesis, structure and electrochemistry of chromium aminocarbyne and phenylcarbyne complexes bearing phosphite or alkyl isonitrile ligands
    J. Organomet. Chem. 1997, 532, 207-218.
    DOI: 10.1016/S0022-328X(96)06749-6
  • A. C. Filippou, B. Lungwitz, G. Kociok-Köhn, I. Hinz
    Half-sandwich rhenium(III) acyl complexes: Synthesis, structure and conversion to rhenium(I) and rhenium(III) isonitrile complexes
    J. Organomet. Chem. 1996, 524, 133-146.
    DOI: 10.1016/S0022-328X(96)06401-7
  • A. C. Filippou, D. Wössner, B. Lungwitz, G. Kociok-Köhn
    Carben-Komplexe des zweiwertigen Chroms
    Angew. Chem. 1996, 108, 981-983; Angew. Chem. Int. Ed. Engl. 1996, 35 , 876-878.
    DOI: 10.1002/anie.199608761
  • G. Kociok-Köhn, B. Lungwitz, A. C. Filippou
    Diisopropylammonium bromide
    Acta Cryst. 1996, C52, 2309-2311.
    DOI: 10.1107/S010827019600354X
  • A. C. Filippou
    Metallzentrierte C-C-Kupplungsreaktionen von C1-Liganden
    45 Jahre Fonds der Chemischen Industrie, Verband der Chemischen Industrie (Hrsg.); Juni 1995, 209-222.
  • A. C. Filippou, B. Lungwitz, K. M. A. Wanninger, E. Herdtweck
    Aminocarbin-Komplexe von Chrom in hoher Oxidationsstufe - Synthese, Struktur und Reaktivität
    Angew. Chem. 1995, 107, 1007-1010; Angew. Chem. Int. Ed. Engl. 1995, 34, 924-927.
    DOI: 10.1002/anie.199509241
  • E. O. Fischer, C. Apostolidis, E. Dornberger, A. C. Filippou, B. Kanellakopulos, B. Lungwitz, J. Müller, B. Powietzka, J. Rebizant, W. Roth
    Carben- und Carbin-Komplexe des Technetiums und Rheniums - Synthese, Struktur und Reaktionen
    Z. Naturforsch. 1995, 50b, 1382-1395.
    DOI: 10.1515/znb-1995-0916
  • A. C. Filippou, B. Lungwitz, C. Völkl, E. Herdtweck
    Metal-Carbon Multiple Bonds: [2+2] Cycloaddition of nitrilium salts across a metalcarbon triple bond; Synthesis and structure of iminocarbene complexes of tungsten
    J. Organomet. Chem. 1995, 502, 131-135.
    DOI: 10.1016/0022-328X(95)05768-K
  • B. Lungwitz, A. C. Filippou
    Metal-Carbon Multiple Bonds: Novel Syntheses and reactions of aminocarbyne complexes of tungsten
    J. Organomet. Chem. 1995, 498, 91-107.
    DOI: 10.1016/0022-328X(95)05483-6
  • A. C. Filippou, C. Mehnert, K. M. A. Wanninger, M. Kleine
    Chromium-Carbon Multiple Bonds: aminocarbyne complexes of chromium bearing isocyanide ligands
    J. Organomet. Chem. 1995, 491, 47-55.
    DOI: 10.1016/0022-328X(94)05208-S
  • A. C. Filippou, C. Völkl, R. D. Rogers
    Metal-centred C-C coupling of nitriles with 1-azaallyl ligands; Synthesis and structure of β-diiminato complexes of tungsten
    J. Organomet. Chem. 1993, 463, 135-142.
    DOI: 10.1016/0022-328X(93)83410-W
  • A. C. Filippou, K. Wanninger, C. Mehnert
    Half-sandwich aminocarbyne complexes of chromium
    J. Organomet. Chem. 1993, 461, 99-109.
    DOI: 10.1016/0022-328X(93)83281-Y
  • A. C. Filippou, P. Hofmann, P. Kiprof, C. Wagner
    Mononuclear bis-aminocarbyne complexes of tungsten with Tp' ligands; theory of metal-centred carbyne-carbyne coupling
    J. Organomet. Chem. 1993, 459, 233-247.
    DOI: 10.1016/0022-328X(93)86076-T
  • B. Lungwitz, A. C. Filippou
    Electron-rich tungsten aminocarbyne complexes with Cp* ligands; Synthesis and protonation reactions
    Transition Metal Carbyne Complexes, NATO ASI Series C, Vol 392, Editor F. R. Kreißl, Kluwer Academic Publishers, Dordrecht, Netherlands, 1993, 249-254.
    DOI: 10.1007/978-94-011-1666-4_28
  • A. C. Filippou, A. R. Dias, A. M. Martins, C. C. Romao
    Isocyanide Derivatives of Tungstenocene
    J. Organomet. Chem. 1993, 455, 129-135.
    DOI: 10.1016/0022-328X(93)80391-N
  • A. C. Filippou, C. Wagner, E. O. Fischer, C. Völkl
    Aktivierung von Ethylisocyanid an elektronenreichen Metallzentren; Synthese von einkernigen Wolfram-Aminocarbin-Komplexen des Typs Tp'(CO)2W≡CN(R)Et (R = Me, Et)
    J. Organomet. Chem. 1992, 438, C15-C22.
    DOI: 10.1016/0022-328X(92)83421-D
  • A. C. Filippou, C. Völkl, W. Grünleitner, P. Kiprof
    Carbyne-carbyne coupling at a single metal center. Synthesis and structure of bis(diethylamino)acetylene complexes of molybdenum(II) and tungsten(II)
    J. Organomet. Chem. 1992, 434, 201-223.
    DOI: 10.1016/0022-328X(92)83306-3
  • H. Nar, R. Huber, A. Messerschmid, A. C. Filippou, M. Barth, M. Jaquinot, M. van de Kamp, G. W. Canters
    Characterization and crystal structure of zinc azurin, a by-product of heterologous expression in Escherichia coli of Pseudomonas aeruginosa copper azurin
    Eur. J. Biochem. 1992, 205, 1123-1129.
    DOI: 10.1111/j.1432-1033.1992.tb16881.x
  • A. M. Martins, M. J. Calhorda, C. C. Romao, C. Völkl, P. Kiprof, A. C. Filippou
    Synthesis and reactivity of molybdenocene isocyanide complexes; Crystal structure of (η5-C5H5)2MoCNtBu
    J. Organomet. Chem. 1992, 423, 367-390.
    DOI: 10.1016/0022-328X(92)83131-Z
  • A. C. Filippou, W. Grünleitner, E. O. Fischer
    Übergangsmetall-Carbin-Komplexe, CII. Alkylierung von Na[CpMo(CO)2CNtBu]; Einfluß des Isocyanid-Substituenten auf den Reaktionsablauf
    J. Organomet. Chem. 1992, 428, C37-C43.
    DOI: 10.1016/0022-328X(92)83107-S
  • A. C. Filippou, W. Grünleitner, C. Völkl, P. Kiprof
    Metal-Centered Coupling of Two Carbyne Ligands To Form an Alkyne Ligand
    Angew. Chem. 1991, 103, 1188-1191; Angew. Chem. Int. Ed. Engl. 1991, 30, 1167-1169.
    DOI: 10.1002/anie.199111671
  • A. C. Filippou, W. Grünleitner;
    Säure-induzierte CC-Kupplung von Isocyanid-Liganden in homoleptischen Alkylisocyanid-Komplexen von Mo(0) und W(0);
    Z. Naturforsch. 1991, 46b, 216-230.
    DOI: 10.1515/znb-1991-0216
  • A. C. Filippou, C. Völkl, P. Kiprof
    Selective synthesis of four- and five-membered metallaheterocycles via C-C bondforming reactions of η2-iminoacyl and η3-1-azaallyl complexes of tungsten with alkylisocyanides
    J. Organomet. Chem. 1991, 415, 375-394.
    DOI: 10.1016/0022-328X(91)80138-A
  • A. C. Filippou, W. Grünleitner, C. Völkl, P. Kiprof
    CC-coupling reactions at low-valent molybdenum centers. Selective formation of η2-iminoacyl, η3-1-azaallyl and η2-1,4-diazabutadien-2-yl complexes of molybdenum from ethylisocyanide complexes
    J. Organomet. Chem. 1991, 413, 181-203.
    DOI: 10.1016/0022-328X(91)80049-P
  • A. C. Filippou, W. Grünleitner, E. O. Fischer, W. Imhof, G. Huttner
    Übergangsmetall-Carbin-Komplexe, XCIX, Synthese und Röntgenstruktur von (η5-C5Me5)(CO)2Mo≡CNEt2 dem ersten, niedervalenten Diethylaminocarbin-Komplex von Molybdän mit einem Pentamethylcyclopentadienyl-Liganden
    J. Organomet. Chem. 1991, 413, 165-179.
    DOI: 10.1016/0022-328X(91)80048-O
  • A. C. Filippou, W. Grünleitner, E. O. Fischer
    Übergangsmetall-Carbin-Komplexe, CI. Gezielter Aufbau eines DiethylaminocarbinLiganden am Wolfram aus Ethylisocyanid-Vorstufen
    J. Organomet. Chem. 1991, 411, C21-C26.
    DOI: 10.1016/0022-328X(91)83053-7
  • A. C. Filippou, W. Grünleitner, P. Kiprof
    Alkylierungsreaktionen eines anionischen Ethylisocyanid-Komplexes von W(0) Synthese von Alkyl-, η2-Iminoacyl-, 1-Azallyl- und Dialkylaminocarbin-Komplexen des Wolframs
    J. Organomet. Chem. 1991, 410, 175-210.
    DOI: 10.1016/0022-328X(91)80006-6
  • A. C. Filippou, W. Grünleitner
    Elektronenreiche isocyanid-substituierte Diethylaminocarbin-Komplexe des Wolframs mit einem Pentamethylcyclopenta-dienyl –Liganden
    J. Organomet. Chem. 1991, 407, 61-79.
    DOI: 10.1016/0022-328X(91)83140-Y
  • A. C. Filippou, W. Grünleitner, E. O. Fischer
    Übergangsmetall-Carbin-Komplexe, C, Synthese elektronenreicher DiethylaminocarbinKomplexe des Wolframs aus Cp(Br)2(CO)W≡CNEt2
    J. Organomet. Chem. 1991, 401, C37-C42.
    DOI: 10.1016/0022-328X(91)86237-K
  • A. C. Filippou, C. Völkl, W. Grünleitner, P. Kiprof
    Basen-induzierte Alkin-Spaltung in W(II)-Komplexen - ein neuer Weg zu niedervalenten Carbin-Komplexen aus W(CO)6
    Z. Naturforsch. 1990, 45b, 351-368.
    DOI: 10.1515/znb-1990-0310
  • A. C. Filippou
    Proton-induced coupling of a tert-butylisocyanide with a diethylaminocarbyne to yield an alkyne ligand at a single tungsten centre
    Polyhedron 1990, 9, 727-738.
    DOI: 10.1016/S0277-5387(00)80282-X
  • A. C. Filippou, C. Völkl, W. Grünleitner, P. Kiprof
    Alkinspaltung als neuer Weg zu niedervalenten Carbinmetallkomplexen
    Angew. Chem. 1990, 102, 224-226; Angew. Chem. Int. Ed. Engl. 1990, 29, 207-209.
    DOI: 10.1002/ange.19901020227
  • A. C. Filippou, W. Grünleitner
    Homoleptic alkylisocyanide complexes of Molybdenum(0) and Tungsten(0), useful precursors for the synthesis of low-valent dialkylaminocarbyne complexes
    J. Organomet. Chem. 1990, 398, 99-115.
    DOI: 10.1016/0022-328X(90)87008-2
  • A. C. Filippou, W. Grünleitner
    Reduktive CC-Kupplung von zwei Isocyanid-Liganden an Mo(II)- und W(II)-Zentren, eine Reaktionssequenz über Isocyanid- und Aminocarbin-Komplexe von Mo(0) und W(0)
    J. Organomet. Chem. 1990, 393, C10-C16.
    DOI: 10.1016/0022-328X(90)87211-U
  • A. C. Filippou, E. O. Fischer, W. Grünleitner
    Übergangsmetall-Carbin-Komplexe, XCVIII. N-Alkylierung eines EthylisocyanidLiganden am Mo(0); Synthese und Oxidationsreaktionen erster cyclopentadienylsubstituierter Molybdän-Diethylaminocarbin-Komplexe
    J. Organomet. Chem. 1990, 386, 333-347.
    DOI: 10.1016/0022-328X(90)80006-L
  • A. C. Filippou, E. O. Fischer
    Übergangsmetall-Carbin-Komplexe, XCVI. Erste, carbonylfreie, neutrale und kationische Phenylcarbin-Komplexe von Wolfram mit Isonitril-Liganden
    J. Organomet. Chem. 1990, 383, 179-190.
    DOI: 10.1016/0022-328X(90)85130-Q
  • A. C. Filippou, E. O. Fischer
    Übergangsmetall-Carbin-Komplexe, XCVII, Carbonylhaltige und carbonylfreie Diethylaminocarbin-Komplexe von Wolfram in einer höheren Oxidationszahl mit Trimethylphosphit- und Isonitril-Liganden
    J. Organomet. Chem. 1990, 382, 143-156.
    DOI: 10.1016/0022-328X(90)85223-L
  • A. C. Filippou
    Synthesis of isonitrile substituted tungsten carbyne complexes and their reactions with electrophiles
    Advances in Metal Carbene Chemistry, Editor U. Schubert, Kluwer Academic Publishers, Dordrecht, Netherlands, 1989, 101-106.
    DOI: 10.1007/978-94-009-2317-1_11
  • A. C. Filippou, W. Grünleitner
    Ein neuer Weg zu cyclopentadienyl-substituierten Diethylaminocarbin-Komplexen des Wolframs
    Z. Naturforsch. 1989, 44b, 1572-1580.
    DOI: 10.1515/znb-1989-1217
  • A. C. Filippou, W. Grünleitner
    Proton-induzierte Kopplung eines tert-Butylisonitril- mit einem Phenylcarbin-Liganden am Wolfram
    Z. Naturforsch. 1989, 44b, 1023-1034.
    DOI: 10.1515/znb-1989-0906
  • A. C. Filippou, W. Grünleitner
    Isonitril-substituierte Halbsandwich-Komplexe von Wolfram(IV)
    Z. Naturforsch. 1989, 44b, 666-672.
    DOI: 10.1515/znb-1989-0609
  • A. C. Filippou
    Cyclopentadienyl substituted diethylaminocarbyne complexes of tungsten in a higher oxidation state
    Polyhedron 1989, 8, 1285-1291.
    DOI: 10.1016/S0277-5387(00)86525-0
  • A. C. Filippou, W. Grünleitner
    Ein neuer Weg zu polyisonitril-substituierten Halbsandwich-Komplexen des zweiwertigen Molybdäns und Wolframs
    J. Organomet. Chem. 1989, 378, 387-399.
    DOI: 10.1016/0022-328X(89)85365-3
  • A. C. Filippou, W. Grünleitner, E. Herdtweck
    Cyclopentadienyl-substituierte Isonitril-Komplexe des vierwertigen Molybdäns; Synthese und Struktur
    J. Organomet. Chem. 1989, 373, 325-342.
    DOI: 10.1016/0022-328X(89)85062-4
  • A. C. Filippou, E. O. Fischer
    Übergangsmetall-Carbin-Komplexe, XCV. Auf dem Weg zu den ersten, carbonylfreien, neutralen und kationischen Diethylaminocarbin-Komplexen des Wolframs
    J. Organomet. Chem. 1989, 365, 317-323.
    DOI: 10.1016/0022-328X(89)87030-5
  • A. C. Filippou, E. Herdtweck, H. G. Alt
    Neue einkernige Triphenylstannyl-substituierte Carben-Komplexe des Kobalts
    J. Organomet. Chem. 1988, 355, 437-447.
    DOI: 10.1016/0022-328X(88)89043-0
  • H. G. Alt, H. Engelhardt, A. C. Filippou
    Acetylen als Baustein für Carben- und Vinylidenliganden am Chrom
    J. Organomet. Chem. 1988, 355, 139-148.
    DOI: 10.1016/0022-328X(88)89017-X
  • A. C. Filippou, E. O. Fischer
    Übergangsmetall-Carbin-Komplexe, XCIV. Reaktionen substituierter Diethylaminocarbin-Komplexe des Wolframs mit Elektrophilen
    J. Organomet. Chem. 1988, 352, 149-155.
    DOI: 10.1016/0022-328X(88)83029-8
  • A. C. Filippou, E. O. Fischer
    Übergangsmetall-Carbin-Komplexe, XCIII. Thermodynamisches Gleichgewicht zwischen einem neutralen und einem kationischen Isonitril-substituierten Diethylaminocarbin-Komplex des Wolframs
    J. Organomet. Chem. 1988, 352, 141-148.
    DOI: 10.1016/0022-328X(88)83028-6
  • A. C. Filippou, E. O. Fischer
    Übergangsmetall-Carbin-Komplexe, XCII. Synthese Pentamethylcyclopentadienylsubstituierter Diethylaminocarbin-Komplexe des Wolframs in niedriger und mittlerer Oxidationszahl
    J. Organomet. Chem. 1988, 349, 367-374.
    DOI: 10.1016/0022-328X(88)87029-3
  • A. C. Filippou, E. O. Fischer, R. Paciello
    Übergangsmetall-Carbin-Komplexe, XCI. Synthese isonitril-substituierter, neutraler und kationischer Diethylaminocarbin-Komplexe des Wolframs in niedriger und mittlerer Oxidationszahl
    J. Organomet. Chem. 1988, 347, 127-136.
    DOI: 10.1016/0022-328X(88)80277-8
  • A. C. Filippou, E. O. Fischer, H. G. Alt
    Übergangsmetall-Carbin-Komplexe, XC. Synthese neuer, siebenfach-koordinierter, kationischer Carbin-Komplexe des Wolframs in einer höheren Oxidationszahl
    Z. Naturforsch. 1988, 43b, 654-657.
    DOI: 10.1515/znb-1988-0603
  • A. C. Filippou, E. O. Fischer, H. G. Alt
    Übergangsmetall-Carbin-Komplexe, LXXXIX. Ein neuer Weg zu kationischen CarbinKomplexen durch reduktive Eliminierung zweier Halogen-Liganden aus neutralen Diethylaminocarbin-Komplexen des Wolframs in einer hohen Oxidationszahl mit PMe3
    J. Organomet. Chem. 1988, 344, 215-225.
    DOI: 10.1016/0022-328X(88)80480-7
  • A. C. Filippou, E. O. Fischer, H. G. Alt
    Übergangsmetall-Carbin-Komplexe, LXXXVIII. Synthese neuer, thermisch stabiler, kationischer DiethylaminocarbinKomplexe des Wolframs
    J. Organomet. Chem. 1988, 340, 331-339.
    DOI: 10.1016/0022-328X(88)80026-3
  • A. C. Filippou, E. O. Fischer
    Übergangsmetall-Carbin-Komplexe, LXXXVII. (η5-C5H5)(I)2(CO)W≡CNEt2, der erste carbonylhaltige DiethylaminocarbinKomplex des Wolframs mit einer hohen Oxidationszahl
    J. Organomet. Chem. 1988, 341, C35-C38.
    DOI: 10.1016/0022-328X(88)89119-8
  • A. C. Filippou, E. O. Fischer, H. G. Alt
    Übergangsmetall-Carben-Komplexe, CXXXXI. Untersuchungen zum Reaktionsverhalten der Carben-Komplexe cis-(CO)4(SnPh3)Re[C(OEt)NR2] (R = ipr, chex) gegenüber Lewis-Säuren
    J. Organomet. Chem. 1987, 330, 325-336.
    DOI: 10.1016/S0022-328X(00)99046-6
  • A. C. Filippou, E. O. Fischer, G. Müller, H. G. Alt
    Übergangsmetall-Carben-Komplexe, CXXXX. Einkernige Triphenylstannyl-substituierte Carben-Komplexe des Rheniums
    J. Organomet. Chem. 1987, 329, 223-239.
    DOI: 10.1016/S0022-328X(00)99796-1
  • A. C. Filippou, E. O. Fischer, J. Okuda
    Übergangsmetall-Carbin-Komplexe, LXXXVI. Synthese mono-, bis- und trisTrimethylphosphan-substituierter Diethylaminocarbin-Komplexe des Wolframs
    J. Organomet. Chem. 1988, 339, 309-321.
    DOI: 10.1016/S0022-328X(00)99392-6
  • A. C. Filippou, E. O. Fischer, H. G. Alt, U. Thewalt
    Übergangsmetall-Carbin-Komplexe, LXXXV. Strukturuntersuchungen der Reaktionsprodukte von trans-Br(CO)2L2WCNEt2 (L2 = 2.2'-Bipyridyl, 1.10-Phenanthrolin) mit den Organylanionen [(CO)5MEPh2]- (M = Cr, Mo, W; E = P, As, Sb)
    J. Organomet. Chem. 1987, 326, 59-81.
    DOI: 10.1016/0022-328X(87)80123-7
  • A. C. Filippou, E. O. Fischer
    Übergangsmetall-Carbin-Komplexe, LXXXIV. Synthese eines neuen fünffach-koordinierten, anionischen Carbin-Komplexes des Wolframs mit einem 1,2-DithiolenLiganden
    J. Organomet. Chem. 1987, 330, C1-C4.
    DOI: 10.1016/0022-328X(87)80297-8
  • A. C. Filippou, E. O. Fischer, H. G. Alt
    Übergangsmetall-Carbin-Komplexe, LXXXIII. Neue anionische mer-Dihalogenotricarbonyl-dialkylaminocarbin-Komplexe des Wolframs
    J. Organomet. Chem. 1986, 310, 357 -366.
    DOI: 10.1016/0022-328X(86)80198-X
  • A. C. Filippou, E. O. Fischer, H. G. Alt
    Übergangsmetall-Carbin-Komplexe, LXXXII. [HCN(C6H5)CH2CH2N(C6H5)]+ [Br2(CO)3WCN(c-C6H11)2]-, Darstellung eines neuen anionischen Carbin-Komplexes des Wolframs durch Umsetzung eines neutralen Carbin-Komplexes mit einem elektronenreichen Olefin
    J. Organomet. Chem. 1986, 303, C13-C16.
    DOI: 10.1016/0022-328X(86)80123-1
  • A. C. Filippou, E. O. Fischer, K. Öfele, H. G. Alt
    Übergangsmetall-Carbin-Komplexe, LXXXI. trans-Ph2As(CO)2(2.2'-bipy)WCNEt2(2.2'-bipy = 2.2'-Bipyridyl), der erste neutrale Diphenylarsano-Carbinkomplex eines Übergangsmetalls
    J. Organomet. Chem. 1986, 308, 11-17.
    DOI: 10.1016/S0022-328X(00)99516-0
  • E. O. Fischer, A. C. Filippou, H. G. Alt
    Übergangsmetall-Carbin-Komplexe, LXXIX. Darstellung und dynamisches Verhalten von cis-Cyanodiethylaminocarbin-Komplexen des Wolframs mit den zweizähnigen Liganden 2.2'-Bipyridyl und 1.10-Phenanthrolin
    J. Organomet. Chem. 1985, 296, 69-82.
    DOI: 10.1016/0022-328X(85)80339-9
  • E. O. Fischer, A. C. Filippou, H. G. Alt, U. Thewalt
    Darstellung von [Et2NC≡W(CO)2(µ-PPh2)2Mo(CO)4]-, des ersten anionischen Carbin-Metall-Komplexes; Addition von CO2 an die W≡C-Bindung
    Angew. Chem. 1985, 97, 215-217; Angew. Chem. Int. Ed. Engl. 1985, 24, 203-205.
    DOI: 10.1002/ange.19850970314
  • E. O. Fischer, A. C. Filippou, H. G. Alt
    Übergangsmetall-Carbin-Komplexe, LXXVI. Neue anionische η2-Keten-Komplexe des Wolframs
    J. Organomet. Chem. 1984, 276, 377-385.
    DOI: 10.1016/0022-328X(84)80659-2
  • E. O. Fischer, A. C. Filippou, H. G. Alt, K. Ackermann
    [(C6H5)3P]2N+ [(ophen)(CO)(CN)2W(η2-C(CO)C6H5)]- (ophen = 1.10-Phenanthrolin), der erste anionische Keten-Komplex eines Übergangsmetalls
    J. Organomet. Chem. 1983, 254, C21-C23.
    DOI: 10.1016/0022-328X(83)85131-6
  • A. C. Filippou, E. O. Fischer
    Synthese thermisch stabiler, neutraler Carbin-Carbonyl-Komplexe von Chrom, Molybdän und Wolfram mit den zweizähnigen Liganden 2.2'-Bipyridyl und 1.10-Phenanthrolin
    Z. Naturforsch. 1983, 38b, 587-591.
    DOI: 10.1515/znb-1983-0511

Selected current publications

The Electronic Nature of Cationic Group 10 Ylidyne Complexes

2023 - The Electronic Nature of Group 10 Ylidyne Complexes
© MDPI

We report a broad theoretical study on [(PMe3)3MER]+ complexes, with M = Ni, Pd, Pt, E = C, Si, Ge, Sn, Pb, and R = ArMes, Tbb, (ArMes = 2,6-dimesitylphenyl; Tbb = C6H2-2,6-[CH(SiMe3)2]2-4-tBu). A few years ago, our group succeeded in obtaining heavier homologues of cationic group 10 carbyne complexes via halide abstraction of the tetrylidene complexes [(PMe3)3M=E(X)R] (X = Cl, Br) using a halide scavenger. The electronic structure and the M-E bonds of the [(PMe3)3MER]+ complexes were analyzed utilizing quantum-chemical tools, such as the Pipek-Mezey orbital localization method, the energy decomposition analysis (EDA), and the extended-transition state method with natural orbitals of chemical valence (ETS-NOCV). The carbyne, silylidyne complexes, and the germylidyne complex [(PMe3)3NiGeArMes]+ are suggested to be tetrylidyne complexes featuring donor-acceptor metal tetrel triple bonds, which are composed of two strong π(M→E) and one weaker σ(E→M) interaction. In comparison, the complexes with M = Pd, Pt; E = Sn, Pb; and R = ArMes are best described as metallotetrylenes and exhibit considerable M-E-C bending, a strong σ(M→E) bond, weakened M-E π-components, and lone pair density at the tetrel atoms. Furthermore, bond cleavage energy (BCE) and bond dissociation energy (BDE) reveal preferred splitting into [M(PMe3)3]+ and [ER] fragments for most complex cations in the range of 293.3-618.3 kJ·mol−1 and 230.4-461.6 kJ·mol−1, respectively. Finally, an extensive study of the potential energy hypersurface varying the M-E-C angle indicates the presence of isomers with M-E-C bond angles of around 95°. Interestingly, these isomers are energetically favored for M = Pd, Pt; E = Sn, Pb; and R = ArMes over the less-bent structures by 13-29 kJ·mol−1.

L. R. Maurer, J. Rump, A. C. Filippou, Inorganics, 2023, 11, 3, 129.


(NHC)Si═C═N–R: A Two-Coordinated Si0-Isocyanide Compound as Si(NHC) Transfer Reagent

2021 - Si0-Isocyanid.jpg
© AK Filippou

Experimental and theoretical studies are reported of the first two-coordinated Si0-isocyanide compound (SIDipp)Si═C═N–ArMes (1: SIDipp (NHC) = C[N(Dipp)CH2]2, ArMes = 2,6-dimesitylphenyl), supported by an N-heterocyclic carbene (NHC). A Si atom economic two-step synthesis of 1 involves a 2e reduction of the isocyanide-stabilized silyliumylidene salt [SiBr(CNArMes)(SIDipp)][B(ArF)4] (2[B(ArF)4], ArF = B(C6H3-3,5-(CF3)2)4) with KC8. 2[B(ArF)4] was obtained from SiBr2(SIDipp) after bromide abstraction with an equimolar mixture of Na[B(ArF)4] and ArMesNC. Exact adherence to the stoichiometry is crucial in the latter reaction, since 2[B(ArF)4] reacts with SiBr2(SIDipp) via isocyanide exchange to afford the disilicon(II) salt [Si2Br3(SIDipp)2)][B(ArF)4] (3[B(ArF)4]), the reaction leading to an equilibrium that favors 3[B(ArF)4] (Keq(298 K) = 10.6, ΔH° = −10.6 kJ mol–1; ΔS° = −16.0 J mol–1 K–1). 3[B(ArF)4] was obtained selectively from the 2:1 reaction of SiBr2(SIDipp) with Na[B(ArF)4] and fully characterized. Detailed studies of 1 reveal an intriguing structure featuring a planar CNHC–Si–C–N skeleton with a V-shaped geometry at the dicoordinated Si0 center, a slightly bent Si═C═N core, a CNHC–Si–CCNR 3c-2e out of plane π-bond (HOMO), and an anticlinal conformation of the SIDipp and ArMes substituents leading to axial chirality and the presence of two enantiomers, (Ra)-1 and (Sa)-1. Compound 1 displays structural dynamics in solution, rapidly interconverting the enantiomers. The silacumulene 1 is a potent Si(SIDipp) transfer agent as demonstrated by the synthesis and full characterization of the NHC-supported germasilyne (Z)-(SIDipp)(Cl)Si═GeArMes (4) from 1 and Ge(ArMes)Cl.

S. Karwasara, L. R. Maurer, B. Peerless, G. Schnakenburg, U. Das, A. C. Filippou, J. Am. Chem. Soc. 2021, 143, 36, 14780–14794.

Highlight: Chemistry Views, 2021


Planar Tetracoordinated Silicon (ptSi): Room-Temperature Stable Compounds Containing Anti-van’t Hoff/Le Bel Silicon

2021 - ptSi.jpg
© AK Filippou

While a variety of compounds containing planar tetracoordinated carbon (ptC), the so-called anti-van’t Hoff/Le Bel carbon, are known experimentally, stable systems containing planar tetracoordinated silicon (ptSi) are barely known. As part of our studies on the application of stereoelectronically well-defined transition-metal fragments to stabilize silicon in unprecedented bonding modes, we report herein the synthesis and full characterization of a series of thermally stable complexes of the general formula [Tp′(CO)2MSiC(R1)C(R2)M(CO)2Tp′] (M = Mo, W; R1 = R2 = Me or R1 = H, R2 = SiMe3, Ph; Tp′ = κ3-N,N′,N″-hydridotris(3,5-dimethylpyrazolyl)borate), which incorporate a ptSi atom in addition to two ptC atoms. The complexes were obtained by reacting the metallasilylidyne complexes [Tp′(CO)2M≡Si–M(CO)2(PMe3)Tp′] with alkynes R1C≡CR2 and were comprehensively analyzed by experimental studies and quantum chemical calculations. The analyses revealed that the ptSi atom is embedded in a tricyclic trapezoidal core featuring one internal SiC2 and two outer M–Si–C three-membered rings, which are fused via two Si–C bonds. The structural peculiarities evoked by the presence of an anti-van’t Hoff/Le Bel ptSi center, such as the short M–Si bonds, a nearly linear M–Si–M spine, long M–C bonds, and the presence of two planar tetracoordinated carbon atoms were elucidated by a detailed analysis of the electronic structure, suggesting that one factor for the stabilization of the ptSi geometry is the aromaticity of the central SiC2 ring having two delocalized π electrons. Remarkably, the results further indicate the existence of both anti-van’t Hoff/Le Bel carbon and silicon centers next to each other in the isolated complexes.

P. Ghana, J. Rump, G. Schnakenburg, M. I. Arz, A. C. Filippou, J. Am. Chem. Soc. 2021, 143, 1, 420–432.

Highlight: Universität Bonn 2020.

Highlight: Chemistry World 2021.


Linearly Two-Coordinated Silicon: Transition Metal Complexes with the Functional Groups M≡Si—M and M═Si═M

2018 - zweifach koordiniertes Silizium.jpeg
© AK Filippou

A detailed experimental and theoretical analysis is presented of unprecedented molybdenum complexes featuring a linearly coordinated, multiply bonded silicon atom. Reaction of SiBr2(SIdipp) (SIdipp = C[N(C6H3-2,6-iPr2)CH2]2) with Na[Tp′Mo(CO)2(PMe3)] (Na-1) in the ratio 1:2 afforded the reddish-brown metallasilylidyne complex [Tp′(CO)2Mo≡Si—Mo(CO)2(PMe3)Tp′] (Tp′ = κ3-N,N′,N″-hydridotris(3,5-dimethylpyrazolyl)borate) (2), in which an almost linearly coordinated silicon atom (∠(Mo1–Si–Mo2) = 162.93(7)°) is bridging the 15VE metal fragment Tp′Mo(CO)2 with the 17VE metal fragment Tp′Mo(CO)2(PMe3) via a short Mo1–Si bond (2.287(2) Å) and a considerably longer Mo2–Si bond (2.438(2) Å), respectively. The reddish-orange silylidyne complex [Tp′(CO)2Mo≡Si—Tbb] (3) was also prepared from Na-1 and the 1,2-dibromodisilene (E)-Tbb(Br)Si═Si(Br)Tbb (Tbb = C6H2-2,6-[CH(SiMe3)2]2-4-tBu) and contains as 2 a short Mo–Si bond (2.2614(9) Å) to an almost linearly coordinated Si atom (∠(Mo–Si–CTbb) = 160.8(1)°). Cyclic voltammetric studies of 2 in diglyme revealed an irreversible reduction of 2 at −1.907 V vs the [Fe(η5-C5Me5)2]+/0 redox couple. Two-electron reduction of 2 with potassium graphite yielded selectively the 1,3-dimetalla-2-silaallene dianion [Tp′(CO)2Mo═Si═Mo(CO)2Tp′]2– (42–), which was isolated as the bright yellow dipotassium salt [K(diglyme)]2-4. Single crystal X-ray diffraction analysis revealed a centrosymmetric structure of 42–. The Mo–Si bond length of 42– (2.3494(2) Å) compares well with those of Mo–Si double bonds and lies in-between the Mo1–Si triple bond and Mo2–Si single bond length of 2. Compounds 2, 3 and [K(diglyme)2]-4 were characterized by elemental analyses, IR and multinuclear NMR spectroscopy. Comparative ELF (electron localization function), NBO (natural bond orbital) and NRT (natural resonance theory) analyses of 2, 3 and 42– shed light into the electronic structures of these compounds. 

P. Ghana, M. I. Arz, U. Chakraborty, G. Schnakenburg, A. C. Filippou, J. Am. Chem. Soc. 2018, 140, 7187.


Metal–Silicon Triple Bonds: Access to [Si(η5-C5Me5)]+ from SiX2(NHC) and its Conversion to the Silylidyne Complex [TpMe(CO)2MoSi(η3-C5Me5)]

2018 - Metall-Silizium Dreifachbindungen.png
© AK Filippou

A novel method to prepare SiCp*2 (1) (Cp* = C5Me5) is presented involving the reaction of N-heterocyclic carbene (NHC)-stabilized SiII halides SiX2(NHC) (X = Cl, Br) with 2 equiv of KCp*. This route is a superior alternative to the laborious, multistep synthesis of 1 presently known and provides via the selective protonolysis of 1 with [H(Et2O)2][B(C6F5)4] facile access to [Si(η5-Cp*)][B(C6F5)4] (2) in multigram scale and high yield. Reaction of 2 with the tailored metallate Na[TpMeMo(CO)2(PMe3)] afforded the unprecedented silylidyne complex [TpMe(CO)2MoSi(η3-Cp*)] (3; TpMe = κ3-N,N′,N″-hydridotris(3,5-dimethyl-1-pyrazolyl)borate). Single crystal X-ray diffraction and spectroscopic studies in combination with quantum chemical calculations shed light on the unique bonding situation of 3 featuring a delocalized Mo–Si bond with partial triple bond character and a Cp* substituent, which is η3-coordinated to silicon.

P. Ghana, M. I. Arz, G. Schnakenburg, M. Straßmann, A. C. Filippou, Organometallics, 2018, 37, 772.


Triple bonds of niobium with silicon, germaniun and tin: the tetrylidyne complexes [(κ3-tmps)(CO)2Nb≡E-R] (E = Si, Ge, Sn; tmps = MeSi(CH2PMe2)3; R = aryl)

2017 - Dreifachbindungen des Niobs mit Silizium.png
© AK Filippou

A systematic, efficient approach to first complexes containing a triple bond between niobium and the elements silicon, germanium or tin is reported. The approach involves a metathetical exchange of the niobium-centered nucleophile (NMe4)[Nb(CO)42-tmps)] (1) (tmps = MeSi(CH2PMe2)3) with a suitable organotetrel(II)halide. Compound 1 was obtained from (NMe4)[Nb(CO)6] and the triphosphane tmps by photodecarbonylation. Reaction of 1 with the disilene E-Tbb(Br)Si=Si(Br)Tbb in the presence of 4-dimethylaminopyridine afforded selectively the red-brown silylidyne complex [(κ3-tmps)(CO)2Nb≡Si–Tbb] (2-Si, Tbb = 4-tert-butyl-2,6-bis(bis(trimethylsilyl)methyl)phenyl). Similarly, treatment of 1 with E(ArMes)Cl (E = Ge, Sn; ArMes = 2,6-mesitylphenyl) afforded after elimination of (NMe4)Cl and two CO ligands the deep magenta colored germylidyne complex [(κ3-tmps)(CO)2Nb≡Ge–ArMes] (3-Ge), and the deep violet, light-sensitive stannylidyne complex [(κ3-tmps)(CO)2Nb≡Sn–ArMes] (3-Sn), respectively. Formation of 3-Sn proceeds via the niobiastannylene [(κ3-tmps)(CO)3Nb–SnArMes] (4-Sn), which was detected by IR and NMR spectroscopy. The niobium tetrylidyne complexes 2-Si, 3-Ge and 3-Sn were fully characterized and their solid-state structures determined by single-crystal X-ray diffraction studies. All complexes feature an almost linear tetrel coordination and the shortest Nb–E bond lengths (d(Nb–Si) = 232.7(2) pm; d(Nb–Ge) = 235.79(4) pm; d(Nb–Sn) = 253.3(1) pm) reported to date. Reaction of 3-Ge with a large excess of H2O afforded upon cleavage of the Nb–Ge triple bond the hydridogermanediol Ge(ArMes)H(OH)2. Photodecarbonylation of [CpNb(CO)4] (Cp = η5-C5H5) in the presence of Ge(ArMes)Cl afforded the red-orange chlorogermylidene complex [Cp(CO)3Nb=Ge(ArMes)Cl] (5-Ge). The molecular structure of 5-Ge features an upright conformation of the germylidene ligand, a trigonal–planar coordinated Ge atom, and a Nb–Ge double bond length of 251.78(6) pm, which lies in-between the Nb–Ge triple bond length of 3-Ge (235.79(4) pm) and a Nb–Ge single bond length (267.3 pm). Cyclic voltammetric studies of 2-Si, 3-Ge, and 3-Sn reveal several electron-transfer steps. One-electron oxidation and reduction of the germylidyne complex of 3-Ge in THF are electrochemically reversible suggesting that both the radical cation and radical anion of 3-Ge are accessible species in solution.

A. C. Filippou, D. Hoffmann, G. Schnakenburg, Chem. Sci. 2017, 8, 6290.


The Femtochemistry of a Ferracyclobutadiene

2017 - Die Femtochemie eines Ferracyclobutadiens
© AK Filippou

The eminent role of metallacyclobutadienes as catalytic intermediates in organic synthesis and polymer chemistry is widely acknowledged. In contrast, their photochemistry is as yet entirely unexplored. Herein, the photo-induced primary processes of a ferracyclobutadiene tricarbonyl complex in solution are revealed by femtosecond mid-infrared spectroscopy. The time-resolved vibrational spectra expose an ultrafast substitution of a basal CO ligand by a solvent molecule in a consecutive dissociation–association mechanism. Following optical excitation, the system relaxes non-radiatively to the triplet ground state from which a CO is expelled. Since the triplet state is bound with respect to Fe−CO cleavage, the dissociation can only occur from vibrationally excited states. The excitation energy, vibrational relaxation, and intersystem crossing to the singlet ground state control the primary quantum yield for formation of the ferracyclic dicarbonyl–solvent product complex.

B. Wezisla, J. Lindner, U.Das, A. C. Filippou, P. Vöhringer, Angew. Chem. Int. Ed. 2017, 56, 6901.


Coordination Chemistry of [E(Idipp)]2+ Ligands (E = Ge, Sn): Metal Germylidyne [Cp*(CO)2W≡Ge(Idipp)]+ and Metallotetrylene [Cp*(CO)3W–E(Idipp)]+ Cations

2017 - Koordinationschemie der Metall-Germylidin und Metallotetrylen Kationen
© AK Filippou

The synthesis and full characterization of the NHC-stabilized tungstenochlorostannylene [Cp*(CO)3W–SnCl(Idipp)] (1Sn), the NHC-stabilized chlorogermylidyne complex [Cp*(CO)2W═GeCl(Idipp)] (2), the tungsten germylidyne complex salt [Cp*(CO)2W≡Ge(Idipp)][B(C6H3-3,5-(CF3)2)4] (3), and the cationic metallostannylene [Cp*(CO)3W–Sn(Idipp)][Al(OC(CF3)3)4] (4Sn) are reported (Idipp = 2,3-dihydro-1,3-bis(2,6-diisopropylphenyl)-1H-imidazol-2-ylidene, Cp* = η5-C5Me5). Metathetical exchange of SnCl2(Idipp) with Li[Cp*W(CO)3] afforded selectively 1Sn. Photolytic decarbonylation of the Ge analogue [Cp*(CO)3W–GeCl(Idipp)] (1Ge) afforded the NHC-stabilized chlorogermylidyne complex (2), featuring a trigonal-planar coordinated germanium center and a W–Ge double bond (W–Ge 2.3496(5) Å). Chloride abstraction from 2 with Na[B(C6H3-3,5-(CF3)2)4] yielded the germylidyne complex salt 3, which contains an almost linear W–Ge–C1 linkage (angle at Ge = 168.7(1)°) and a W–Ge triple bond (2.2813(4) Å). Chloride elimination from 1Ge afforded the tungstenogermylene salt [Cp*(CO)3W–Ge(Idipp)][B(C6H3-3,5-(CF3)2)4] (4Ge), which in contrast to 1Ge could not be decarbonylated to form 3 despite the less strongly bound carbonyl ligands. The tin compounds 1Sn and 4Sn did not afford products bearing multiple W–Sn bonds. Treatment of 4Ge with Me2NC≡CNMe2 yielded unexpectedly the neutral germyl complex 5 containing a pendant 1-germabicyclo-[3,2,0]-hepta-2,5-diene ligand instead of the anticipated [2 + 1]-cycloaddition product at the Ge-center.

Y. N. Lebedev, U. Das, G. Schnakenburg, A. C. Filippou, Organometallics 2017, 36, 1530.


NHC-stabilized Silicon(II) Halides: Reactivity Studies with Diazoalkanes and Azides

2016 - NHC-stabilisierte Silizium(II)-Halogenide
© AK Filippou

Detailed studies of the reactivity of the NHC-stabilized (NHC = N-heterocyclic carbene) silicon(II) halides SiI2(Idipp) (1) and SiClR(IMe4) (2-Trip: R = ArTrip; 2-Mes: R = ArMes) towards diazoalkanes and azides are presented (Idipp = C[N(C6H3–2,6-iPr2)CH]2, IMe4 = C[N(Me)CMe]2, ArTrip = C6H3-2,6-Trip2, ArMes = C6H3-2,6-Mes2, Trip = C6H2-2,4,6-iPr3, Mes = C6H2-2,4,6-Me3). Treatment of 1, 2-Trip, and 2-Mes with the diazoalkanes (p-Tol)2CN2 (p-Tol = C6H4-4-Me) and ArMesCHN2 afforded the NHC-stabilized silazines SiI2{N2C(p-Tol)2}(Idipp) (3) and SiClR{N2CH(ArMes)}(IMe4) (4-Trip: R = ArTrip, 4-Mes: R = ArMes) as orange to yellow solids, respectively. No N2 elimination from the diazoalkanes was observed in these reactions. In comparison, the reactions of 1 or 2-Trip with the covalent azides MesN3 or Me3SiN3, yielded after N2 elimination the yellow to colorless NHC-stabilized silaimines SiI2(NMes)(Idipp) (5), Si(ArTrip)Cl(NMes)(IMe4) (6) and Si(ArTrip)(N3)(NSiMe3)(IMe4) (7), respectively. All compounds were characterized by elemental analyses, FT-IR and multinuclear magnetic resonance spectroscopy. Moreover, the molecular structures of 4-Mes, 5, 6, and 7 were determined by single-crystal X-ray diffraction analyses.

M. I. Arz, D. Hoffmann, G. Schnakenburg, A. C. Filippou Z. Anorg. Allg. Chem. 2016, 642, 1287.


The Si2H radical supported by two N-heterocyclic carbenes

2016 - Si2H Radikal
© AK Filippou

Cyclic voltammetric studies of the hydridodisilicon(0,II) borate [(Idipp)(H)SiII=Si0(Idipp)][B(ArF)4] (1H[B(ArF)4], Idipp = C[N(C6H3-2,6-iPr2)CH]2, ArF = C6H3-3,5-(CF3)2) reveal a reversible one-electron reduction at a low redox potential (E1/2 = −2.15 V vs. Fc+/Fc). Chemical reduction of 1H[B(ArF)4] with KC8 affords selectively the green, room-temperature stable mixed-valent disilicon(0,I) hydride Si2(H)(Idipp)2 (1H), in which the highly reactive Si2H molecule is trapped between two N-heterocyclic carbenes (NHCs). The molecular and electronic structure of 1H was investigated by a combination of experimental and theoretical methods and reveals the presence of a π-type radical featuring a terminal bonded H atom at a flattened trigonal pyramidal coordinated Si center, that is connected via a Si–Si bond to a bent two-coordinated Si center carrying a lone pair of electrons. The unpaired electron occupies the Si=Si π* orbital leading to a formal Si–Si bond order of 1.5. Extensive delocalization of the spin density occurs via conjugation with the coplanar arranged NHC rings with the higher spin density lying on the site of the two-coordinated silicon atom.

M. I. Arz, G. Schnakenburg, A. Meyer, O. Schiemann, A. C. Filippou Chem. Sci. 2016, 7, 4973.


Addition of Small Electrophiles to N-Heterocyclic-Carbene-Stabilized Disilicon(0): A Revisit of the Isolobal Concept in Low-Valent Silicon Chemistry

2016 - Addition von kleinen Elektrophlen an Disilizium(0)
© AK Filippou

Protonation and alkylation of (Idipp)Si═Si(Idipp) (1) afforded the mixed-valent disilicon(I)-borates [(Idipp)(R)SiII═Si0(Idipp)][B(ArF)4] (1R[B(ArF)4]; R = H, Me, Et; ArF = C6H3-3,5-(CF3)2; Idipp = C[N(C6H3-2,6-iPr2)CH]2) as red to orange colored, highly air-sensitive solids, which were characterized by single-crystal X-ray diffraction, IR spectroscopy and multinuclear NMR spectroscopy. Dynamic NMR studies in solution revealed a degenerate isomerization (topomerization) of the “σ-bonded” tautomers of 1H[B(ArF)4], which proceeds according to quantum chemical calculations via a NHC-stabilized (NHC = N-heterocyclic carbene) disilahydronium ion (“π-bonded” isomer) and is reminiscent of the degenerate rearrangement of carbenium ions formed upon protonation of olefins. The topomerization of 1H[B(ArF)4] provides the first example of a reversible 1,2-H migration along a Si═Si bond observed in a molecular system. In contrast, 1Me[B(ArF)4] adopts a “rigid” structure in solution due to the higher energy required for the interconversion of the “σ-bonded” isomer into a putative NHC-stabilized disilamethonium ion. Addition of alkali metal borates to 1 afforded the alkali metal disilicon(0) borates 1M[BAr4] (M = Li, Ar = C6F5; M = Na, Ar = ArF) as brown, air-sensitive solids. Single-crystal X-ray diffraction analyses and NMR spectroscopic studies of 1M[BAr4] suggest in concert with quantum chemical calculations that encapsulation of the alkali metal cations in the cavity of 1 predominantly occurs via electrostatic cation−π interactions with the Si═Si π-bond and the peripheral NHC aryl rings. Displacement of the [Si(NHC)] fragments by the isolobal fragments [PR] and [SiR] interrelates the cations [(NHC)(R)Si═Si(NHC)]+ to a series of familiar, multiply bonded Si and P compounds as verified by analyses of their electronic structures.

M. I. Arz, M. Straßmann, D. Geiß, G. Schnakenburg, A. C. Filippou J. Am. Chem. Soc. 2016, 138, 4589.


Photochemistry of a Puckered Ferracyclobutadiene in Liquid Solution Studied by Time-Resolved Fourier-Transform Infrared Spectroscopy

2015 - Photochemie eines gefalteten Ferrazyclobutadiens
© AK Filippou

Flash photolysis combined with step-scan and rapid-scan Fourier-transform infrared spectroscopy was carried out to explore the photochemistry of a puckered, quasi-square pyramidal ferracyclobutadiene, [Fe{κ2-C3(NEt2)3}(CO)3]BF4 ([1]BF4), that features three additional carbonyl ligands in the metal coordination sphere. In liquid solution at room temperature, an excitation with λ=355 nm light resulted in the loss of one CO ligand, which is cleaved from a basal metal-coordination site. Within the time resolution of the experiment, a solvent molecule promptly refills the resultant vacancy at the coordinatively unsaturated metal center. In the weakly interacting liquid, dichloromethane, the counterion of the complex is subsequently able to substitute the solvent in the coordination sphere of the iron center, thereby forming as a stable product a neutral dicarbonyl tetrafluoroborato iron(0) species containing a four-membered ferracycle.

J. Torres-Alacan, U. Das, B. Wezisla, M. Straßmann, A. C. Filippou, P. Vöhringer Chem. Eur. J. 2015, 21, 17184.


Silicon(i) chemistry: the NHC-stabilised silicon(i) halides Si2X2(Idipp)2 (X = Br, I) and the disilicon(i)-iodido cation [Si2(I)(Idipp)2]+

2015 - Silizium(I) Chemie
© AK Filippou

An efficient method for the synthesis of the NHC-stabilised Si(I) halides Si2X2(Idipp)2 (2-X, X = Cl, Br, I; Idipp = C[N(C6H3-2,6-iPr2)CH]2) was developed, which involves the oxidation of Si2(Idipp)2 (1) with 1,2-dihaloethanes. Halogenation of 1 is a diastereoselective reaction leading exclusively to a racemic mixture of the RR and SS enantiomers of 2-X. Compounds 2-Br and 2-I were characterised by single-crystal X-ray crystallography and multinuclear NMR spectroscopy, and their electronic structures were analysed by quantum chemical methods. Dynamic NMR spectroscopy unraveled a fluxional process of 2-Br and 2-I in solution, which involved a hindered rotation of the NHC groups about the Si–CNHC bonds. Iodide abstraction from 2-I by [Li(Et2O)2.5][B(C6F5)4] selectively afforded the disilicon(I) salt [Si2(I)(Idipp)2][B(C6F5)4] (3). X-ray crystallography and variable-temperature NMR spectroscopy of 3 in combination with quantum chemical calculations shed light on the ground-state geometric and electronic structure of the [Si2(I)(Idipp)2]+ ion, which features a Si=Si bond between a trigonal planar coordinated SiII atom with a Si–I bond and a two-coordinate Si0 center carrying a lone pair of electrons. The dynamics of the [Si2(I)(Idipp)2]+ ion were studied in solution by variable-temperature NMR spectroscopy and they involve a topomerisation, which proceeds according to quantum theory via a disilaiodonium intermediate (“π-bonded” isomer) and exchanges the two heterotopic Si sites.

M. I. Arz, D. Geiß, M. Straßmann, G. Schnakenburg, A. Filippou Chem. Sci. 2015, 6, 6515.


One-Electron Oxidation of a Disilicon(0) Compound: An Experimental and Theoretical Study of [Si2]+ Trapped by N-Heterocyclic Carbenes

2015 - Einelektronen-Oxidation einer Disilizium(0) Verbindung
© AK Filippou

One-electron oxidation of the disilicon(0) compound Si2(Idipp)2 (1, Idipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) with [Fe(C5Me5)2][B(ArF)4] (ArF=C6H3-3,5-(CF3)2) affords selectively the green radical salt [Si2(Idipp)2][B(ArF)4] (1-[B(ArF)4). Oxidation of the centrosymmetric 1 occurs reversibly at a low redox potential (E1/2=−1.250 V vs. Fc+/Fc), and is accompanied by considerable structural changes as shown by single-crystal X-ray structural analysis of 1-B(ArF)4. These include a shortening of the Si-Si bond, a widening of the Si-Si-CNHC angles, and a lowering of the symmetry, leading to a quite different conformation of the NHC substituents at the two inequivalent Si sites in 1+. Comparative quantum chemical calculations of 1 and 1+ indicate that electron ejection occurs from the symmetric (n+) combination of the Si lone pairs (HOMO). EPR studies of 1-B(ArF)4 in frozen solution verified the inequivalency of the two Si sites observed in the solid-state, and point in agreement with the theoretical results to an almost equal distribution of the spin density over the two Si atoms, leading to quite similar 29Si hyperfine coupling tensors in 1+. EPR studies of 1-B(ArF)4 in liquid solution unraveled a topomerization with a low activation barrier that interconverts the two Si sites in 1+.

M. I. Arz, M. Straßmann, A. Meyer, G. Schnakenburg, O. Schiemann, A. Filippou Chem. Eur. J. 2015, 21, 12509.


Si=Si Double Bonds: Synthesis of an NHC-Stabilized Disilavinylidene

2015 - Si=Si Doppelbindungen
© AK Filippou

An efficient two-step synthesis of the first NHC-stabilized disilavinylidene (Z)-(SIdipp)Si=Si(Br)Tbb (2; SIdipp=C[N(C6H3-2,6-iPr2)CH2]2, Tbb=C6H2-2,6-[CH(SiMe3)2]2-4-tBu, NHC=N-heterocyclic carbene) is reported. The first step of the procedure involved a 2:1 reaction of SiBr2(SIdipp) with the 1,2-dibromodisilene (E)-Tbb(Br)Si=Si(Br)Tbb at 100 °C, which afforded selectively an unprecedented NHC-stabilized bromo(silyl)silylene, namely SiBr(SiBr2Tbb)(SIdipp) (1). Alternatively, compound 1 could be obtained from the 2:1 reaction of SiBr2(SIdipp) with LiTbb at low temperature. 1 was then selectively reduced with C8K to give the NHC-stabilized disilavinylidene 2. Both low-valent silicon compounds were comprehensively characterized by X-ray diffraction analysis, multinuclear NMR spectroscopy, and elemental analyses. Additionally, the electronic structure of 2 was studied by various quantum-chemical methods.

P. Ghana, M. I. Arz, U. Das, G. Schnakenburg, A. C. Filippou Angew. Chem. Int. Ed. 2015, 54, 9980.


Si=P Double Bonds: Experimental and Theoretical Study of an NHC-Stabilized Phosphasilenylidene

2015 - Si=P Doppelbindungen
© AK Filippou

An experimental and theoretical study of the first compound featuring a Si=P bond to a two-coordinate silicon atom is reported. The NHC-stabilized phosphasilenylidene (IDipp)Si=PMes* (IDipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene, Mes*=2,4,6-tBu3C6H2) was prepared by SiMe3Cl elimination from SiCl2(IDipp) and LiP(Mes*)SiMe3 and characterized by X-ray crystallography, NMR spectroscopy, cyclic voltammetry, and UV/Vis spectroscopy. It has a planar trans-bent geometry with a short Si=P distance of 2.1188(7) Å and acute bonding angles at Si (96.90(6)°) and P (95.38(6)°). The bonding parameters indicate the presence of a Si=P bond with a lone electron pair of high s-character at Si and P, in agreement with natural bond orbital (NBO) analysis. Comparative cyclic voltammetric and UV/Vis spectroscopic experiments of this compound, the disilicon(0) compound (IDipp)Si=Si(IDipp), and the diphosphene Mes*P=PMes* reveal, in combination with quantum chemical calculations, the isolobal relationship of the three double-bond systems.

D. Geiß, M. I. Arz, M. Straßmann, G. Schnakenburg, A. C. Filippou, Angew. Chem. 2015, 127, 2777.


[2+2+1] Cycloadditions of Bis(dialkylamino)acetylenes with SiI2(Idip): Syntheses and Reactivity Studies of Unprecedented 2,3,4,5-Tetraamino-1 H-siloles

2014 - Cycloaddition
© AK Filippou

A novel method for the synthesis of 1H-siloles is presented. It involves a [2+2+1] cycloaddition of the ynediamines R2N—C≡C—NR2 (R=Me, Et) with SiI2(Idip) (Idip=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) to afford the orange-colored, highly water-sensitive 1,1-diiodo-2,3,4,5-tetraamino-1H-siloles SiI2{C4(NR2)4} (1-I: R=Me; 2-I R=Et). Treatment of 2-I with an excess of SiBr4 afforded after I/Br exchange the 1,1-dibromo-1H-silole SiBr2{C4(NEt2)4} (2-Br). The 1H-siloles 1-I, 2-I, and 2-Br were fully characterized and their molecular structures determined by single-crystal X-ray diffraction. The compounds feature a slightly twisted five-membered silacyclopenta-2,4-diene ring and a double/single C—C bond alternation in the diene fragment. Reaction of 2-I with the N-heterocyclic carbene IMe4 (IMe4=1,3,4,5-tetramethylimidazolin-2-ylidene) leads, after displacement of the iodide groups, to the unprecedented diiodide salt [Si(IMe4)2{C4(NEt2)4}](I)2 (3), containing a 1H-silole dication with a four-coordinate SiIV center. The crystal structure of 3 reveals similar bonding characteristics for the dicationic 1H-silole to those of the neutral 1H-siloles 1-I2-Br. Two-electron reduction of 3 with C8K affords, after elimination of one IMe4 group, the thermolabile, carbene-stabilized 1-silacyclopentadien-1-ylidene Si{C4(NEt2)4}(IMe4) (4), which was characterized by elemental analysis and 1H, 13C{1H}, and 29Si{1H} NMR spectroscopies.

Y. N. Lebedev, U. Das, O. Chernov, G. Schnakenburg, A. C. Filippou Chem. Eur. J, 2014, 20, 9280.


Silicon–Oxygen Double Bonds: A Stable Silanone with a Trigonal-Planar Coordinated Silicon Center

2014 - Silizium-Sauerstoff-Doppelbindungen
© AK Filippou

Si=O in a complex: The first silanone that is stable at room temperature (3) is reported. The two-step synthesis involves carbonylation of the silylidyne complex 1 to give the chromiosilylene 2, followed by oxidation of 2 with N2O. Silanone 3 features a polar, short Si=O bond (1.526(3) Å) to a trigonal-planar-coordinated silicon center and reacts with water to give the dihydroxysilyl complex.

A. C. Filippou, B. Baars, O. Chernov, Y. N. Lebedev, G. Schnakenburg Angew. Chem. 2014, 126, 576.

S. S. Sen, Angew. Chem., 2014, 126, 8964.

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