A paramagnetic 1:1 adduct of triphenylphosphine and bis(diethyldihiophosphato)nickel(II)

Abstract

Square planar bis(diethy1dithiophosphato)nickel(I1) forms a stable, paramagnetic, 1:l adduct with triphenylphosphine which in solution undergoes rapid triphenylphosphine exchange.ALTHOUGH a variety of bases are known to form both 1 : l and 2:l adducts in solution with square planar bis(dialky1 dithiophosphato)nickel(II), only 2 : 1 six co-ordinate adducts have been isolated and characterized. 1-4 The six co-ordinate adducts have been the subject of a number of recent spectroscopic investigations. 1 We report that triphenylphosphine reacts readily with Ni(dtp),, [dtp = (EtO),PS,-] to form dark green crystals of the first example of a 1:1, five co-ordinate adduct of Ni(dtp), isolated in the solid state, K, = 1.2 f 0.3 1 mol-l, E (6000 A) = 154 f : 5.All attempts to prepare the 2:l adduct failed. A spectral analysis indicated that only a 1:l adduct is formed in solution with metal :triphenylphosphine mole ratios of up to 470:l. The ease with which the 1 : l complex could be isolated is in marked contrast with the impossibility of