Comprehensive Study of the Reactions Between Chelating Phosphines and Ni(cod)(2)

A comprehensive study of the reactions of chelating phosphines with Ni(cod)(2) to form (phosphine)Ni(cod), (phosphine)(2)Ni, or mixtures thereof is presented. A series of (phosphine)Ni(cod) complexes were isolated and characterized. The structural differences between the (phosphine)Ni(cod) and (phosphine)(2) Ni complexes were examined using X-ray crystallography and H-1 and P-31 NMR spectroscopy. In addition, the effects of ring size, rigidity, and bulk of the phosphine backbone on the formation of either (phosphine)Ni(cod) or (phosphine)(2)Ni were investigated. These studies show that the Ni-P bond lengths in both the (phosphine)Ni(cod) and (phosphine)(2)Ni complexes and the size of the ring formed by the chelating phosphine and Ni are crucial in determining whether or not (phosphine)Ni(cod) complexes can be isolated. Other factors such as Jr-stacking interactions were found to have marginal influence.