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Reaction Mechanisms

Our current work focuses on the investigation of reaction mechanisms in both solution and the gas phase. By using electrospray ionziation, species present in solution can often be directly observed in the mass spectrometer. The elemental composition of the detected ions is determined unequivocally by exact mass measurements. The oxidation state becomes evident in the charge state. Induced fragmentation of mass-selected species (MS/MS) is a possibility to obtain information on the structure of the observed intermediates. The FT-ICR mass spectrometer is particularly well suited for these investigations. In addition, ion/molecule reactions in the highly diluted gas phase of the ultra-high vaccuum of the FT-ICR cell reveal the intrinsic reactivity of defined species. A comparison of gas phase and solution phase behavior provides insight into solvation effects.
Currently, we are working on reactions in the fields of organocatalysis and metal organic chemistry. One example of our research is the project B3 "Solution- and Gas-Phase Studies of Open-Shell Ferracyclobutadienes" in the SFB 813 "Chemistry of Spin Centers".


  • Probing the gas-phase structure of charge-tagged intermediates of a proline catalyzed aldol reaction – Vibrational spectroscopy distinguishes oxazolidinone from enamine species
    J. A. Willms, J. Vidic, J. Barthelmes, V. Steinmetz, T. Bredow, P. Maître, M. Engeser, Phys. Chem. Chem. Phys. 2019, 21, 2578 - 2586.
    DOI: 10.1039/C8CP04905J
  • Mechanistic studies of a L-proline-catalyzed pyridazine formation involving a Diels-Alder reaction with inverse electron demand
    A. Schnell, J. A. Willms, S. Nozinovic, M. Engeser, Beilstein J. Org. Chem. 2019, 15, 30-43.
    DOI: 10.3762/bjoc.15.3
  • Investigations of the copper catalyzed oxidative cross-coupling of THIQs with diethylzinc with a combination of mass spectrometric and electrochemical methods
    J. A. Willms, H. Gleich, M. Schrempp, D. Menche, M. Engeser, Chem. Eur. J. 2018, 24, 2663-2668.
    DOI: 10.1002/chem.201704914
  • A new charge-tagged proline-based organocatalyst for mechanistic studies using electrospray mass spectrometry
    J. A. Willms, R. Beel, M. L. Schmidt, C. Mundt, M. Engeser,  Beilstein J. Org. Chem. 2014, 10, 2027-2037.
    DOI: 10.3762/bjoc.10.211
  • Iron azides with cyclam derived ligands: Are they precursors for high-valent iron nitrides in the gas phase?
    O. Krahe, F. Neese, M. Engeser, ChemPlusChem  2013, 78, 1053-1057.
    DOI: 10.1002/cplu.201300182

  • Direct experimental evidence for an enamine radical cation in SOMO catalysis
    R. Beel, S. Kobialka, M. L. Schmidt, M. Engeser, Chem. Comm. 2011, 47, 3293-3295.  
    DOI: 10.1039/c0cc05347c

  • Room-Temperature C-H Bond Activation of Methane by Bare [P4O10] .+
    N. Dietl, M. Engeser, H. Schwarz, Angew. Chem. 2009, 121, 4955-4957; Angew. Chem. Int. Ed. 2009, 48, 4861-4863.
    DOI: 10.1002/ange.200901596 bzw. 10.1002/anie.200901596
    highlighted in:
    R. H. Crabtree, Nature Chemistry 2009, 1, 348-349. DOI: 10.1038/nchem.311


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