Reactions of electroneutral alkoxy(organo)carbene complexes of platinum(II)

Abstract

The carbene complexes cis-[PtCl₂(PR₃){C(OR′)(CH₂R″)}](1; R₃= Me₂Ph or Et₃; R′= Me, Et, or Prⁿ; R″= Me, Et, or Ph) react rapidly with CD₃OD to yield cis-[PtCl₂(PR₃){C(OR′)(CD₂R″)}], then slowly by alkoxy-group exchange to cis-[PtCl₂(PR₃){C(OCD₃)(CD₂R″)}]. Dimethylamine reacts by proton abstraction to form [PtCl(PR₃)(NMe₂H){C(OR′)CHR″}]. The carbene complexes react with chloride ions by R′Cl elimination to form the acyls [Pt₂(µ-Cl)₂(PR₃)₂(COCH₂R″)₂]. Thermolyses of (1) produce the same products. These reactions are compared with those of related cationic carbene complexes. Treatment of (1) by PR₃ in the presence of Ag-[S(CF₃)O₃] leads to the cationic carbene complex trans-[PtCl(PR₃)₂{C(OR′)(CH₂R″)}][S(CF₃)O₃] which can also be made by the action of R′SO₃CF₃ on trans-[PtCl(PR₃)₂(COCH₂R″)]. Halogen abstraction from (1) by Ag[S(CF₃)O₃], MeSO₃CF₃, or EtSO₃CF₃ produces binuclear halide-bridged cationic complexes [Pt₂(µ-Cl)₂(PR₃)₂{C(OR′)(CH₂R″)}₂][S(CF₃)O₃]₂. These are extremely powerful alkylating agents, and alkylate the [S(CF₃)O₃]^– anions in solution.