Coordination chemistry of perhalogenated cyclyopentadienes and alkynes—XXI. Studies on the substitution reactions of Pt(PPh 3) 2(C 2Cl 2) and trans-Pt(PPh 3) 2(Cl)(C 2Cl) with triphenylphosphite

Abstract

The reactions of the Pt(0) π-alkyne complex Pt(PPh 3) 2(Cl CCCl) and the Pt II alkynyl complex Pt(PPh 3) 2(Cl)(CCCl) with P(OPh) 3 lead to either the π-alkyne complexes Pt(PPh 3) n (P(OPh) 3) 2− n (Cl CCCl) ( n = 0, 1) or the cis and trans isomers of Pt(PPh 3) n [P(OPh) 3] 2− n (Cl)(CCCl) ( n = 0, 1), depending on the reactions conditions. The course of the reaction was followed by 31P-NMR spectroscopy, from which a plausible mechanism for the oxidative addition reaction can be derived : key steps are phosphine dissociation from the Pt(0) species to a two-coordinate intermediate, which undergoes oxidative addition of a CCl bond to give a three-coordinate Pt II species, which might be stabilized by dimerization.