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.