Organosilyl- and silylorgano-pentaboranes: monocarbahexaboranes from 2-[(chlorodimethylsilyl)methyl]pentaborane(9)

Abstract

Bridge and terminally substituted pentaborane(9) derivatives of the type [(ClCH₂)Me₂Si] B₅H₈, have been prepared. Rearrangement of both the 1- and 2-terminally substituted pentaboranecompounds to the carbon-attached isomers, 1- and 2-[(ClMe₂Si)CH₂] B₅H₈, is accomplished with the use of AlCl₃ as catalyst. Flash thermolysis of 2-[(ClMe₂Si)-CH₂] B₅H₈ yields SiMe₂ClH (48%), B₅CH₉(4.2%), and B₅CH₇(9.4%) as the major volatile products. Alkylation of B₅H₉ with SiMe₃(CH₂Cl) in the presence of AlCl₃, gives 1 -MeB₅H₈ and SiMe₃Cl in quantitative amounts, whereas use of Si(CH₂Cl)Cl₃ as the alkylating agent gives only 1-[(Cl₃Si)CH₂]Br₅H₈.