Some square-planar alkoxo- and hydroxo-complexes of Group 8: preparation, bonding, and novel condensation reactions with active methyl compounds

Abstract

A series of mononuclear methoxo-complexes. cis- and trans-[MR(OMe)(PPh₃)₂](M = Pd or Pt; R = aryl or alkenyl) has been prepared by metathesis of [MR(Cl)(PPh₃)₂] with Na(OMe). Hydrolysis of the methoxo-complexes gives corresponding hydroxo-complexes. trans-[MR(OH)(PPh₃)₂], which are also obtained from [MR(OCMe₂)(PPh₃)₂]⁺ and [OH]^–. The stability and nature of the M–OR bond (R = H or Me) are influenced markedly by the identity of the metal and the trans ligand, R. The anionic character of the OH or OR ligand increases in the orders Pt < Pd and C₆F₅ < CClCCl₂ < CHCCl₂ < Ph. The hydroxo-complexes react with PhCOMe and MeNO₂ to give the corresponding condensates. trans-[PtR(CH₂X)(PPh₃)₂](X = COPh or NO₂). The condensation reaction is facilitated by the increase in anionic character of the OH ligand.