The Simultaneous Conversion of Ni-PR3 and B-H to Ni-H and B-PR3 Linkages by Thermal Rearrangement of d8-Closo-Bis(triarylphosphine)Nickelacarboranes. Crystal and Molecular Structure of (Closo-3-mu-CO-8-PPh3-3,1,2-NiC2B9H10)2; a Dimeric Nickelacarborane Complex Containing a Metal-Metal Bond.

Abstract : The reaction of L2NiC12 (L=PR3) species with nido-7,8-,-7,9-, or -2,9-C2B9H112- ions led to the formation of the corresponding icosahedral bis(phosphine)nickelacarboranes in high yield. Heating members of the closo-3,3-(triarylphosphine)2-3-H-3,1,2-NiC2B9H11 by interchange of phosphine and hydrido ligands. No intermediates were observed and the reaction was specific for the bis(triarylphosphine)-3,1,2-NiC2 icosahedral system among those investigated. A dimeric nickelacarborane carbonyl closo-(-3-U-CO-8-PPh3-3,1,2-NiC2B9H11)2 was prepared by a variety of routes such as the reaction of closo-3,3-(PPh3)2-3,1,2-NiC2B9H11 (la), with CO in benzene at 80 C. A variety of ligand substitution reactions were carried out with la. The mechanism of the phosphine-hydride ligand interchange is discussed. The dimeric nickelacarborane complex was characterized by an X-ray diffraction study.