Vorträge-Koll

Bio-inspired catalysts for clean H₂ production Hydrogen production through water splitting emerges as a pertinent solution in the long run for renewable energy storage. Hydrogenases, which are organometallic enzymes containing iron and/or nickel metal centers, exhibit catalytic performances that rival platinum for hydrogen evolution. Their fascinating properties make them the ideal inspiration for designing molecular catalysts for technological devices. During this presentation, the bio-inspired strategy will be illustrated: How can this approach be at the origin of efficient systems that achieve H₂ production in a catalytic manner? How can it provide helpful information regarding the catalytic mechanism of the enzymes?

"Pnictaalumenes and Pn,Al-Heterocycles"⠀ Heavier element–element multiple bonds had been long considered inaccessible but have now moved beyond the status of lab curiosities. The number of heteroatomic E¹³═E¹⁵ (E¹³ = Al, Ga; E¹⁵ = N, P, As) multiple bonds is still limited. Due to alternating Lewis acidic and Lewis basic centers, E¹³=E¹⁵ species are prone to oligomerize. Oligomerization should be suppressed by either kinetic, acceptor or donor stabilization. In this lecture the facile synthesis of pnictaalumenes and -gallenes is described, afforded by the combination of Pnicta-Wittig reagents of the type ArPn(PMe₃) (Ar = terphenyls; Pn = P, As) with sources of Al(I) opr Ga(I), respectively. This afforded ^DipTerPn=AlCp*, compounds with Pn-Al multiple bond character. The reactivities of ^DipTerPnAlCp* towards small molecules such as CO₂, C2H4, C2H2, and azides are discussed.

Zur diesjährigen Weihnachtsvorlesung mit vielen Experimenten sind Studierende, Mitarbeiter*innen, Kolleg*innen und Chemieinteressierte herzlich eingeladen. Schulklassen werden um vorherige Anmeldung gebeten. Für alle anderen Interessenten, z. B. Studierende, ist keine Anmeldung erforderlich. Bitte beachten Sie jedoch, dass die Anzahl an Plätzen in den Hörsälen begrenzt ist.

Universität Bonn - "Non-alkyne Like Reactivity of Ditetrelynes E₂R₂ (E = Si, Ge)"⠀ In contrast to alkynes, their heavier ditetrel analogues called ditetrelynes E₂R₂ (E = Si - Pb) possess a pseudo Jahn-Teller distorted <i>trans-bent</i> core and two non-degenerate π bonds. This peculiar geometric and electronic structure leads to unparalleled reactivity. It is addressed in the present lecture by unprecedented reactions of ditetrelynes with metal carbonyls and low-valent silicon compounds. Special emphasis will be given on - a) the 1,3-dipolar cycloaddition chemistry of a cobalt digermyne complex, b) the carbonyl migratory insertion chemistry into a Si≡Si triple bond, and c) the metathetical exchange of a Ge≡Ge triple bond.

Universität Bonn - "Co≡E (E = Si – Pb) Triple Bonds: Cobalt-Centered Cleavage of E≡E Bonds and Co≡E Metathetic Exchange Reactions" <i>[Abstract: tba]</i>

"Crystal growth by Chemical Vapor Transport" In recent years, a large number of compounds from different classes - intermetallic phases, pnictides, oxides, chalcogenides and halides - have been crystallized at the MPI CPfS by chemical vapor transport. After rare earth metal compounds with complex anions, pnictide chalcogenides and monophosphides or arsenides of niobium and tantalum, the research focus at the moment is on the crystallization of intermetallic compounds crystallizing in the FeSi structure type and dichalcogenides of some transition metals. The grown crystals have been made available for various collaborative projects to study their physical and chemical properties. The development of physical measurement methods to increasingly sensitive systems opens new perspectives for chemical vapor transport. Crystals, which were previously unsuitable for measurements due to their small size, can now be characterized very precisely in terms of their physical properties.

Westfälische Wilhelms-Universität Münster - "Reactivity of Amido-Substituted Silicon Ring and Cluster Compounds" In my talk different synthetic pathways to unsaturated amido-substituted silicon ring and cluster compounds will be introduced. By modifications of the steric and electronic properties of the amido substituent we can access different silicon ring and clusters compounds with diverse electronic properties. These compounds feature a pair of three-coordinate silicon atoms with zwitterionic character and low-coordinate silicon atoms that we want to exploit for activation of strong bonds in small molecules such as NH₃, BH₃, CO₂, H₂, MeOH and alkenes and alkynes. Beyond that, starting from a bicyclic silicon(I) ring compound we found access to novel silicon chalcogenide cage compounds with silicon in different low-oxidation states and to a so-called silylone with an additional Si=N double bond. [...]