Monomeric phosphido and phosphinidene complexes of nickel

An unusual family of three-coordinate, d8 and d9 nickel phosphido and phosphinidene complexes containing the chelating 1,2-bis(di-tert-butylphosphino)ethane (dtbpe) ligand and a terminal PR2- or PR2- ligand have been prepared. The complexes (dtbpe)Ni{P(t-Bu)2} (2), [(dtbpe)Ni{=P(t-Bu)2}+][PF6-] (3), [(dtbpe)Ni{=P(H)(dmp)}+][PF6-] (5), and (dtbpe)Ni{=P(dmp)} (6) have been structurally characterized by single-crystal X-ray diffraction methods. The three-coordinate d8 complexes exhibit Ni-P bond lengths and ligand geometries that indicate they participate in symmetry-allowed ligand-to-metal π bonding involving phosphorus p-electrons and a metal-orbital of π symmetry that lies in the Ni coordination plane. Compound 6 is a rare example of a late-transition-metal terminal phosphinidene complex. Copyright © 2002 American Chemical Society.