BASE STABILIZATION OF FUNCTIONALIZED SILYLENE TRANSITION-METAL COMPLEXES

The dehydrogenative coupling reaction of primary silanes ArSiH3 [Ar = [2-(Me(2)NCH(2))C6H4], [8-(Me(2)NCH(2))C10H6], [8-(Me(2)N)C6H4]] with Fe(CO)(5), Cr(CO)(6), CpCo(CO)(2), and RCpMn(CO)(3) (R = H, CH3) under photolytic conditions affords an effective access to intramolecular base-stabilized functionalized silanediyl-transition metal complexes of general formula [ArHSi=MLn]. Si-29-NMR investigations of the photochemical reaction of PhSiH(3) with Fe(CO)(5) in the presence of 1,3-dimethyl-2-imidazolidinone (DMI) or hexamethylphosphoric triamide indicates a two-step mechanism for the formation of base-stabilized silanediyl-transition metal complexes. The carbonyl displacement reactions of the complex [2-(Me(2)-NCH2)C6H4]HSi=Cr(CO)(5) in the presence of PPh(3) or P(OMe)(3) lead to the formation of trans-(PPh(3))(2)Cr(CO)(4) or trans-[P(OMe)(3)]Cr-2(CO)(4), respectively, either by photolysis or by thermolysis. Photochemical displacement reaction with (diphenylphosphino)ethane furnished [2-(Me(2)NCH(2))C6H4]HSi=Cr[Ph(3)(CH2)(2)PPh(2)](CO)(3) by subsequent displacement of two carbonyls of the metal moiety. Exchange reactions of the complex [2-(Me(2)NCH(2))C6H4]HSi=Cr(CO)(5) with Ph(3)CX (X = Cl, BF4, OSO2CF3) or CH(3)COX' (X' = Cl, Pr) provide a direct entry to a series of functionalized complexes [2-(Me(2)NCH(2))C6H4]XSi=Cr(CO)(5). The liberated silylenes from complexes ArHSi(B)=Fe(CO)(4) (Ar = Ph, 1-Np) (B = DMI) can be trapped in the presence of tert-butyl alcohol or methanol to give di-tert-butoxysilanes or trimethoxysilanes, respectively.