Electrophilic cleavage reactions of carbon-silicon bonds in neutral hexacoordinate silicon compounds: diorgano(phtalocyaninato)silicon

Article abstract of DOI:10.1016/0022-328X(88)89072-7

Preparations of diorgano(phtalocyaninato)silicon <(Pc)Si(R¹)(R²)> and their reactions with N-bromosuccinimide (NBS), halogens, copper(II) halides, and 3-chloroperbenzoic acid (MCPBA) are reported.The alkyl-silicon bonds are readily cleaved by NBS, halogens, and CuX2 to give the corresponding alkyl halides.The reactivity of aryl-silicon bonds toward NBS and halogen depends greatly on the electronic effect of the substituent on the benzene ring, but these bonds are almost inert to CuX2.The reactivity of the carbon-silicon bond towards NBS cleavage decreases in the order 4-MeOC6H4 > n-C8H17 > 4-MeC6H4 > Ph >> 3-CF3C6H4.Cleavage of alkyl-silicon bonds may involv one-electron transfer from substrate to reagent and alkyl radical intermediates, while the electrophilic aromatic substitution mechanism may operate in the cleavage of aryl-silicon bonds. <(Pc)SiR2> are stable to MCPBA.