The crystal and molecular structure of trans-bis(triethylphosphine)di(phenylethynyl)nickel

The structure of trans-bis(triethylphosphine)di(phenylethynyl)nickel has been determined by X-ray methods. The co-ordination round the nickel atom is square-planar, and the molecule has the approximate symmetry 2/m. The acetylide group is σ-bonded to the nickel atom via one carbon atom, and the Ni–C bond has the normal singlebond length; the Ni–P bond however is shorter than in related halide complexes. The stability of organo-metallic complexes of this type is attributed to two main causes; the high ligand-field strength of all four ligands, and π-type bonding between the metal and phosphorus atoms, resulting from an inductive effect exerted by the relatively electropositive carbon donor atoms which encourages electron transfer away from the negative ligand and towards the phosphine ligand.