cis and trans Palladium(II) and platinum(II) complexes with 1,8-bis(diphenylphosphino)-3,6-dioxaoctane and their structural characterization. The first example of an eleven-membered diphosphine chelate involving cis geometry

Abstract

Monomeric cis and trans complexes of Pt^II and Pd^II with 1,8-bis(diphenylphosphino)3,6-dioxaoctane (dpdo) of general formulae [M(dpdo)X₂](M = Pd, X = Cl, Br, I, or NCS; M = Pt, X = Cl or I), in which the ligand binds only by the two phosphine donor atoms, have been synthesized and characterized by i.r., electronic, and ³¹P n.m.r, spectroscopy and molecular weight measurements. The isolation of these complexes illustrates that both cis and trans 11-membered chelate rings are obtainable under appropriate conditions; for example, both cis- and trans-monomeric [Pt(dpdo)Cl₂] are reported. Syntheses of cis-palladium(II) complexes were carried out in polar solvents while trans isomers were prepared in less polar solvents. cis-Platinum complexes were prepared from [PtCl₄]^2– while the trans isomers were prepared from Zeise's salt. Crystal structures of cis-[Pd(dpdo)Cl₂] and trans-[Pd(dpdo)I₂] are reported and discussed.