Kuniyuki Kishikawa

Synthesis and characterization of an extremely hindered tetraaryl-substituted digermene and its unique properties in the solid state and in solution

Abstract 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 (Δ H =14.7±0.2 kcal mol −1 and Δ S =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 O 2 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.

Synthesis and Reactions of a 1-Germaallene Kinetically Stabilized by 2,4,6-Tris[Bis(Trimethylsilyl)Methyl]Phenyl Group

Treatment of an extremely hindered alkylidenetelluragermirane with a large excess amount of hexamethylphosphorous triamide resulted in the formation of the first stable I-germaallene, which was also synthesized by reductive dechlorination of the corresponding overcrowded (l-chlorovinyl)chlorogermane with t-butyllithium in THF. The germaallene was isolated as a colorless solid by the latter synthetic method and found to be fairly stable even in solution at room temperature, although it underwent an intramolecular cyclization at 80 °C in benzene.

Synthesis of Novel Germaheterocycles Using Low-Coordinated Germanium Species

Abstract Some novel four−, five−, and six-membered germaheterocycles are synthesized using low-coordinated germanium species such as Tbt(Tip)Ge, Tbt(Tip)Ge=X(X=O, S, Se, Te)(Tbt=2,4,6-tris[bis(trimethylsilyl)methyl]phenyl; Tip=2,4,6-triisopropylphenyl).

Synthesis And Reactions Of The First Stable 1-Germaallene 1,2-Telluride And Its Sulfur And Selenium Analogues

The first stable 1-germaallene 1,2-telluride and its sulfur and selenium analogues are synthesized by the addition of chalcogen source to the reaction mixture of germanium divalent species such as Tbt(Mes)Ge: (Tbt = 2,4,6-tris[bis(trimethylsilyl) methyl]-phenyl; Mes = mesityl) and α,α-dichloroalkene.

Synthesis and structure of the first germaketenedithioacetal

Treatment of an overcrowded diarylgermylene Tbt(Tip)Ge: 1{Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, Tip = 2,4,6-triisopropylphenyl} with carbon disulfide affords the first germaketenedithioacetal derivative 3 as a stable orange crystalline compound, for which the molecular structure is established by X-ray crystallographic analysis.