Transition metal–carbon bonds. Part XXX. Internal metallations of platinum(II)-t-butyldi-o-tolylphosphine and -di-t-butyl-o-tolyphosphine complexes

Abstract

Platinum(II) complexes of the phosphines PBu^t(o-tolyl)₂ and PBu^t₂(o-tolyl) have been prepared. The internally metallated compounds trans-[PtCl(P–C)L][(P′–C)= CH₂C₆H₄PBu^t(o-tolyl) or (P″–C)= CH₂C₆H₄PBu^t₂; L = PBu^t(o-tolyl)₂ or PBu^t₂(o-tolyl)] are very readily formed by treating Na₂PtCl₄ or trans-[PtCl₂(PhCN)₂] with L. The metallation occurs at the tolyl-methyl of the ligand, L, in all cases. For complexes of the type [PtX(P′–C) PBu^t-(o-tolyl)₂](X = Cl, NO₃, or Me), metallation of the PBu^t(o-tolyl)₂ ligand goes less readily to give the dimetallated complexes cis-[Pt(P′–C)₂] or trans-[Pt(P′–C)₂]. The tendency to metallate increases in the order of anionic ligands X = Cl < Me [graphic omitted] NO₃. The compound trans-[Pt(P″–C)₂] is prepared by heating [PtMe(P″–C)PBu^t₂(o-tolyl)]. Bridged complexes of the type [Pt₂Cl₂(P–C)₂] are readily prepared and the chloride bridges replaced on treatment with silver carboxylate to give the compounds [Pt₂X₂(P–C)₂](X = OAc or OBz). The chloride bridges are also split by various ligands (e.g. pyridine, PPh₃, acetylacetonate, etc) giving monomeric species.