157220-68-3Relevant academic research and scientific papers
Synthesis and characterization of an extremely hindered tetraaryl-substituted digermene and its unique properties in the solid state and in solution
Tokitoh, Norihiro,Kishikawa, Kuniyuki,Okazaki, Renji,Sasamori, Takahiro,Nakata, Norio,Takeda, Nobuhiro
, p. 563 - 577 (2008/10/08)
An extremely hindered digermene (E)-Tbt(Mes)Ge=Ge(Mes)Tbt (1; Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl; Mes = mesityl) was synthesized. X-ray crystallographic analysis of the hexane solvated single crystal [1·0.5hexane] revealed that 1 has an extremely long germanium-germanium double bond [2.416(2) A?] as that of a carbon-substituted digermene. The temperature-dependent change of UV-Vis absorption of digermene 1 in solution indicated the quantitative interconversion between 1 and the corresponding germylene Tbt(Mes)Ge: (3). The thermodynamic parameters (ΔH = 14.7 ± 0.2 kcal mol-1 and ΔS = 42.4 ± 0.8 cal mol-1 deg-1) for the dissociation of digermene 1 to germylene 3 were obtained from temperature dependence of the absorption of 1. Since the reactivity of germylene 3 is much higher than that of digermene 1, almost all the intermolecular reactions of 1 in solution proceeded via dissociated 3. For instance, the reaction of 1 with oxygen in solution resulted in a non-stereospecific formation of the cis- and trans-1,3,2,4-dioxadigermetanes 11 and 7 via the initial formation of germanone 12 derived from oxygenation of the dissociated germylene 3. In case of the oxidation in the solid state, however, digermene 1 reacted with O2 without dissociation to give the corresponding trans-substituted 1,3,2,4-dioxadigermetane stereospecifically. The reaction of digermene 1 with W(CO)5(THF) was also examined to give the corresponding terminal tungsten complex of the dissociated germylene 3, i.e. Tbt(Mes)Ge=W(CO)5 (23), as a marginally stable orange yellow paste.
