Metal–olefin complexes. Part II. Some palladium(II) and platinum(II) derivatives of tris(but-3-enyl)arsine containing co-ordinated and unco-ordinated olefinic groups

Abstract

The potentially quadridentate chelate, tris(but-3-enyl)arsine, reacts with palladium(II) salts to form PdLX₂(X = Cl, I) complexes, and with platinum(II) salts to form PtLX₂(X = Cl, Br, I,CNS) complexes. The complexes have been investigated by conductivity measurements, molecular weight studies, and by electronic, i.r., and ¹H n.m.r. spectroscopy. The PdLCl₂ and PtLX₂(X = Cl, Br) complexes are cis-planar and, as well as containing an arsine donor, also contain a co-ordinated olefinic group in rapid equilibrium with unco-ordinated olefins. The PdLI₂ and PtLX₂(X = I, CNS) are halogeno- or pseudohalogeno-bridged dimers and contain only monodentate arsine-donor ligands. The tendency for olefins to co-ordinate in these, and analogous systems, is discussed.