Ligand-protected strain-free diarylgermylenes

Reaction of 2 molar equiv of 2,6-di(1′-naphthyl)phenyllithium with bis[bis(trimethylsilyl)-amino]germylene afforded the red, crystalline, stable bis[2,6-bis(1-naphthyl)phenyl]germylene [(bisap)₂Ge, 6] in good yield. The structure of the solvate 6·C₆H₆ was determined by single-crystal X-ray methods. The molecule features a largely strain-free conformation with a C-Ge-C angle of 102.72(9)° and Ge-C distances of 2.036(2) and 2.030(2) Å. These parameters are very close to those calculated for the diphenylgermylene prototype by ab initio methods [101.6°, 2.006 Å]. The two new wing-like 2,6-di(1-naphthyl)phenyl substituents appear to protect the germylene center of 6 in a very efficient way without inducing destabilizing distortions. Bis[2,4,6-triphenyl]germylene [(triph)₂Ge, 1] was also prepared. Germylenes 1 and 6 were oxidized to yellow products of the composition (triph)₂GeO (2) and (bisap)₂GeO (7), respectively. The compounds have been characterized by their mass spectra, which show the parent ions in full accordance with the proposed formulas.