Reactions of an Isolable Dialkylgermylene with Acyl Chlorides Forming Acyl(chloro)germanes and Diacylgermanes

The reactions of
isolable dialkylgermylene 1 with
benzoyl and substituted benzoyl chlorides afford the corresponding
aroyl­(chloro)­germanes in high yields. While 2,2-dimethylpropanoyl
chloride reacts similarly, the reactions of more reactive alkanoyl
chlorides such as acetyl, propanoyl, and butanoyl chlorides give rather
unexpectedly the corresponding dialkanoylgermanes 3 together
with alkanoyl­(chloro)­germanes 2 (2:3 = 4:1). Aroyl- and alkanoyl­(chloro)­germanes 2a–2g and dialkanoylgermanes 3e–3g obtained were fully characterized by multinuclear NMR spectroscopy,
high-resolution mass spectrometry (HRMS), and by single-crystal X-ray
diffraction studies for 2a and 3f. UV–vis
spectra of 3e–3g and a TDDFT study
of the model diacylgermanes showed two separated n → π*
absorption bands, suggesting significant electronic interaction between
the two carbonyl groups in a molecule through the central germanium
atom.