Co-ordination complexes containing multidentate ligands. Part XI. Transition-metal derivatives of 1,3-bis(3′-dimethylarsinopropylthio)propane, a facultative quadridentate ligand with diverse donor properties

Abstract

The synthesis of the facultative quadridentate ligand. 1,3-bis(3′-dimethylarsinopropylthio)propane (L), is described. Twenty complexes of Co^II, Ni^II, Pd^II, and Pt^II have been prepared and the variety of the resulting stereochemistries demonstrates the utility of open-chain ligands in allowing such factors as electronic properties of the metal ions, nature of the solvent, and counter ions to also dictate structure. tans-Pseudo-octahedral [NiX₂L] complexes are obtained for X = Cl, Br, or NCS, but for X = I the diamagnetic [NiIL]I results. The [NiCl₂L] complex undergoes facile transformation to planar [NiL]X₂, via a trigonal-bipyramidal intermediate. An unusual type of trans-chelating bidentate behaviour is observed on dissolving [MXL]⁺(M = Pd or Pt) complexes, which have a MAs₂S₂X donor set in the solid state and in nitromethane. in halogeno-organic solvents to form planar [MX₂L] species with the donor set MAs₂X₂.