Transition-metal complexes containing phosphorus ligands. Part X. ortho-Metallation reactions involving some triaryl phosphite derivatives of palladium(II) and platinum(II) dihalides

Abstract

Triaryl phosphite complexes of palladium(II) and platinum(II), MX₂[P(OAr)₃]₂(M = Pd or Pt; X = Cl, Br, or I; Ar = phenyl, p-chlorophenyl, o-, m-, or p-tolyl), react in boiling decalin, with elimination of a molecule of hydrogen halide. HX, to afford ortho-metallated triaryl phosphite derivatives. The tendency to undergo metallation is dependent upon the anionic ligands present and increases I < Br < Cl. The structures and stereochemistry of these products have been determined by i.r. and n.m.r. spectroscopy. Treatment of the ortho-metallated complexes with hydrogen halide in dichloromethane leads to rapid reversal of the ortho-palladation reactions and slow reversal of the ortho-platination reactions. Mechanistic aspects of the ortho-metallation processes are discussed.