New nickel–carbon dioxide complex: synthesis, properties, and crystallographic characterization of (carbon dioxide)-bis(tricyclohexylphosphine)nickel

Ni (CO2) (PCy3) 2, 0·75 (C7H8), where Cy = cyclohexyl, can be made either by treating Ni (PCy3) 3 or Ni (PCy3) 22N2 with CO2 in toluene, or by direct reduction of NiBr2 (PCy3) 2 with sodium sand under CO2; the complex is planar, the CO2 ligand possesses bent geometry and is co-ordinated through the carbon atom and one of the oxygen atoms.