Catalytically Active Borohydride-Reduced Nickel and Cobalt Systems

Catalytic systems based upon nickel or cobalt compounds and sodium borohydride give a remarkable variety of products of wide application depending upon the reaction conditions. However, the information on these systems is widely scattered throughout the technical inorganic and organic literature. The object of this review, therefore, is to summarize and correlate what has been written about these catalytic systems and to stimulate practical industrial applications of them. Until recently, these studies were somewhat empirical in nature and we will therefore review in addition recent studies concerning the complex mechanism of Ni11 and CO11 reductions with borohydride ion. Particular attention will be given to recently published organoruckel and organocobalt complex compound structures (of as yet unexamined catalytic activity) prepared from the appropriate M11 salts and sodium borohydride in the presence of a variety of ligands.