Erlangen 2022 – scientific programme

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MO: Fachverband Molekülphysik

MO 14: Photochemistry II

MO 14.3: Talk

Wednesday, March 16, 2022, 15:00–15:15, MO-H6

Reversible (photo)chemistry of Cr(0), Mo(0) and W(0) carbonyl complexes — •Sophie Steiger¹, Pit Boden¹, Patrick Di Martino-Fumo¹, Tobias Bens², Daniel Marhöfer¹, Biprajit Sarkar², Gereon Niedner-Schatteburg¹, and Markus Gerhards¹ — ¹TUK, FB Chemie, Erwin-Schrödinger-Str. 52, 67663 Kaiserslautern — ²University of Stuttgart, Institute of Inorganic Coordination Chemistry, Pfaffenwaldring 55, 70569 Stuttgart

This contribution presents the investigations of the photochemical reactivity of chromium, molybdenum and tungsten carbonyl complexes containing a bidental pyridyl-mesoionic carbene ligand. The photochemical reactivity of these complexes in pyridine, acetonitrile or in a KBr pellet was analysed by rapid-scan FTIR spectroscopy or by recording static FTIR spectroscopy at defined time intervals. Hereby, the carbonyl stretching vibrations represented suitable IR probes. In the dark after excitation, a reverse reaction to the initial species occurs. The influence of the metal centre and the solvent on the kinetics of the reverse reaction in solution and the quantum yield of the initial photochemical reaction were determined.

Quantum chemical calculations were performed for conceivable photoproducts to characterise the underlying reaction. The loss of an axial CO ligand was assigned to the photoproduct in the solid state at low temperature, with subsequent occupation of the vacant coordination site by a solvent molecule in fluid solution. This interpretation simultaneously explains the appearance of a signal of free CO in the FTIR spectra.