Tris(trimethylsilyl)methyl-lead oxinates: their solvolysis, redistribution, and reductive elimination reactions

Abstract

The complex PbMe2[C(SiMe3)3](ox)(where ox = the anion of 8-hydroxyquinoline) is stable to boiling ethanol over short periods, but on prolonged heating undergoes redistribution and reductive elimination reactions yielding Pb(ox)2, PbMe3(ox), PbMe3[C(SiMe3)3], and 8-methoxyquinoline. By contrast, when PbCl2Me[C(SiMe3)3] is treated with 8-hydroxyquinoline at pH ca. 10 in methanol, ethanol, or aqueous dioxan the bis(trimethylsilyl)methyl complex PbMe[CH(SiMe3)2](ox)2(1) is formed together with SiMe3(OR)(R = H, Me, or Et) rather than the expected tris(trimethylsilyl)methyl complex. Refluxing (1) in ethanol or aqueous dioxan results in further nucleophilic displacement of SiMe3 groups yielding, successively, PbMe(CH2SiMe3)(ox)2(2) and PbMe2(ox)2(3). These cleavage reactions occur in competition with disproportionation and reductive elimination processes, the final products derived from (3) being Pb(ox)2, PbMe4, PbMe3(ox), and 8-methoxyquinoline. The corresponding 8-hydroxy-2-methylquinolinate complexes are also examined.