Carbenoid-mediated formation and activation of element-element and element–hydrogen bonds

Abstract

The application of the silyl-substituted Li/Cl carbenoid RR'C(Li)Cl ($\bf 1$) [with R = Ph$_2$P(S), R' = SiMe$_3$] in the dehydrocoupling of group 14 element hydrides is reported. While silanes only yield product mixtures, selective E–E bond formation was observed for germanes and stannanes. In case of the tin compounds, also aliphatic stannanes could be successfully coupled to the corresponding distannanes. This reactivity is in contrast to that reported for BH$_3$, which preferentially undergoes B–H addition to the carbenoid carbon atom via borate formation. Formation of a borate intermediate is also assumed to be the initial step in the reaction of ($\bf 1$ with phosphinoborane CatB-PPh$_2$ (Cat = catecholato), which results in the generation of diphosphine Ph$_4$P$_2$ via chlorotrimethylsilane elimination and formation of a 1,1'-diborylated carbanion