The reaction of Ni[S,P(OMe),],with Ph,P*C,H,.AsPh, in benzene-dichloromethane gives [S,PO(OMe)] -(Ph,P*C,H,.AsPh2)Ni,0~5C6H6.The crystal structure of this compound has been determined by Patterson and Fourier methods from three-dimensional X-ray photographic data. Crystals are monoclinic, space group P2,/c, with a = 9.30(1), b = 17.37(1), c = 20.13(1) 8, p = 108.87(2)", Z = 4. Refinement by least-squares methods gave a conventional R of 0.09 for 3852 independent non-zero reflections.The nickel atom is co-ordinated in an approximately square-planar configuration of chromophore [NiS,PAs],the sulphur donor being the novel ligand [S2PO(OMe)l2-. Features of the molecular geometry are discussed.The same reaction is given by 1,2-bis(diphenylphosphino)ethane but not by the arsino-analogue, which instead gives a poorly characterised 1 :I adduct with Ni[S,P(OMe),12.BIS( DIALKYL PHOSPHORODITHIOATO)-and bis(dialky1-phosp1iinodithioato)-nickel(I1) complexes, Ni[S,P(OR),], and Ni( S,PR,),, readily form five-and six-co-ordinate complexes with nitrogen-donor ligands in non-aqueous so1ution.l The latter are easily separated as solids and their spectral properties and stereochemistry have been reported., The five-co-ordinate complexes do not normally give stable solids and only Ni[S,P(OMe),],-(2,9-dimethylphenanthroline), a distorted trigonal bipyramid, and Ni(S,PEt,),(quinoline), a distorted square pyramid, have been fully characterised by crystalstructure analysis. Few complexes of these [NiS,] chromophores are known with donor ligands other than nitrogen, except for Ni[S,P(OEt>,],(PPh,), which is believed to have a square-based pyramidal high-spin configuration on the basis of magnetic moment and electronic ~p e c t r a . ~ W7e report the reactions between the bidentate ligands Ph,P*C,H,-PPh, (dpe) , the mixed phosphinoarsino-analogue (dpae), and the diarsine (dae) with Ni[S,P(OMe),],.The intention was to prepare fivet Part 111, preceding paper.
