Nickel (II) and cobalt (II) complexes of cis - 1,2, bis (diphenylphosphino) ethylene

Abstract Nickel(II) and cobalt(II) complexes with 1,2- cis (diphenylphosphino) ethylene are reported. Magnetic susceptibility, infrared and visible spectra, and conductivity studies have been made. The existence of a spin-free spin-paired equilibrium is proposed for the nickel(II) nitrate complex. The magnetic properties and infrared data are discussed in terms of possible structures for the complexes. The magnetic moments of the nickel(II) complexes are intermediate between the values expected from a diamagnetic ana paramagnetic species. The moment for the cobalt(II) complexes are normal from species with one unpaired electron. The infrared spectra of the complexes do not show the presence of coordinate nitrate or per chlorate anions. However, the appearance of the CC stretching absorption, which is infrared inactive for the uncomplexed, symmetrical ligand indicates that some asymmetry exists about the double bond in the solid complexes