Gas-phase synthesis and characterization of heteroleptic divalent germanium compounds by FVT/UV-PES

The flash vacuum thermolysis/UV photoelectron spectroscopic (FVT/UV-PES) technique has been applied for the synthesis of three cyclic germanediyls containing oxo-thio, oxo-amino, and thio-amino substitution at germanium. The three compounds (4b, 5b and 6b) were prepared from the corresponding 3,4-dimethyl-1-germacyclopent-3-enes (4a, 5a and 6a) by thermal cheletropic elimination, and the photoelectron spectra of both sets of molecules were measured. The course of the thermolysis reactions has also been confirmed by mass spectrometric methods and the results of chemical trapping experiments. The assignment of the PE spectral bands for the two series of molecules has been carried out with the aid of time dependent DFT (TD-DFT) and outer valence green’s function (OVGF) calculations. The results indicate that the strong σ-withdrawing effect of oxygen and the strong π-donating effect of nitrogen are the two main factors affecting the electronic structures of these germylene derivatives.