Reactions of halogenohydridobis(triethylphosphine)platinum(II) with trihalogenophosphines: some unusual complexes of PtII containing five-co-ordinated phosphorus

Abstract

³¹ P N.m.r. spectra show that [PtClH(PEt₃)₂] reacts with PCl₃ in CH₂Cl₂ at 180 K to give [PtCl₂H₂(PEt₃)₂], (5), and the previously unknown [PtCl(PEt₃)₂(P′Cl₂)], (4). On warming to 240 K, complex (5) decomposes and (4) is reversibly protonated to give [PtCl(PEt₃)₂(P′Cl₂H)]⁺. Above 240 K, (4) is converted into the novel [PtCl(PEt₃)₂(P′Cl₂H₂)], (8). This complex is stable in solution up to 260 K, but decomposes irreversibly at higher temperatures. Changes in the n.m.r. spectra on adding HCl or BCl₃ are interpreted in terms of dissociation of (8) into [PtCl(PEt₃)₂(P′ClH₂)]⁺ and [HCl₂]^– or [BCl₄]^–. Reaction of [PtBrH(PEt₃)₂] with PBr₃ at 160 K gives [PtBr₂H(PEt₃)₂(P′Br₂)], which loses HBr at 190 K, giving [PtBr(PEt₃)₂(P′Br₂)] and [PtBr₂H₂(PEt₃)₂]. At 240 K, [PtBr(PEt₃)₂(P′Br₂H₂)] is produced. This persists for short periods at room temperature, and is stable at 170 K; addition of HBr or BBr₃ leads to the formation of [PtBr(PEt₃)₂(P′BrH₂)]⁺ by loss of bromide ion. All these species were identified by n.m.r. spectroscopy.