The chemistry of germanium-containing heavy ketones

The recent applications of an extremely bulky and efficient steric protecti on group, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (denoted as Tbt in th is article), to the kinetic stabilization of a series of doubly bonded comp ounds between germanium and heavier chalcogen atoms (we coin the expression "germanium-containing heavy ketones" for this family of heavier congeners of germanone) are described. Combination of a Tbt group with some other bul ky aromatic or alkyl substituent enabled us to synthesize the novel germani um-containing double-bond species [Tbt(R)Ge=X; R = 2,4, 6-triisopropylpheny l (Tip) or bis(trimethylsilyl)methyl (Dis)] such as germanethiones (X = S), germaneselones (X = Se), and germanetellones (X = Te) as stable crystallin e compounds, while the germanone [Tbt(Tip)Ge=O], the most reactive species among the germanium-containing heavy ketones, was found to be very difficul t to isolate and was evidenced only by the trapping reactions. The X-ray cr ystallographic analysis of the isolated germanium-containing heavy ketones revealed a completely trigonal planar geometry around their germachalcogeno carbonyl units and their ideally doubly bonded character, which was also co nfirmed by their spectroscopic data.