抄録
The first stable germabenzene 2 bearing an efficient steric protection group, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt), was successfully synthesized by the reaction of the corresponding chlorogermane 3 with lithium diisopropylamide in THF. The molecular structure and aromaticity of 2 were discussed on the basis of its NMR, UV-vis and Raman spectra, X-ray crystallo-graphic analysis and theoretical calculations. All 1H and 13C NMR chemical shifts of the germabenzene ring of 2 were in good agreement with those calculated. UV-vis and Raman spectra of 2 showed similar patterns to those of benzene, suggesting the structural similarity between germabenzene and benzene. X-ray crystallographic analysis of 2 revealed that the germabenzene ring was almost planar indicating the delocalization of π-electrons. 2 reacted smoothly with water to give both 1, 2- and 1, 4-adducts, 4a and 4b. Reactions of 2 with 2,3-dimethyl-1,3-butadiene and styrene afforded the corresponding 1, 2- and 1, 4-cycloadducts 5 and 6, respectively. Furthermore, the ligand exchange reaction of [Cr(CH3CN)3(CO)3] with 2 resulted in the formation of the first stable germabenzene Cr complex 7.
