The application of a cobalt pincer complex, (PP Cl P)CoCl 2 , as a precatalyst for the hydroboration of terminal alkenes with pinacolborane (HBPin) is described. The reactions proceed rapidly under mild conditions (room temperature, 30 min) with low catalyst loadings (1 mol %) using KBEt 3 H (2.1 mol %) as an activator to afford terminal hydroboration products with very high selectivity for the anti-Markovnikov product. The precatalyst is effective toward vinyl arenes and aliphatic alkenes and proceeds to an 83−98% yield with these substrates. However, the functional group tolerance of the catalytic system is somewhat limited, as minimal conversion is observed with internal olefins or when pyridine, ketone, or allyl ether functional groups are present. Deuterium labeling studies and spectroscopic identification of the catalyst deactivation product suggest a (PPP)CoH active species.

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A Co(II) complex, (PP H P)CoI 2 , was synthesized and evaluated as a precatalyst for the hydrogenation of terminal alkenes under mild conditions (1 atm H 2 , ambient temperature) using KBEt 3 H as an activator. This catalytic system was found to be active for terminal alkene substrates, including 1,1′-disubstituted alkenes, and to exhibit modest air and moisture stability. A preliminary investigation into substrate scope and functional group tolerance was performed. Upon the completion of catalytic reactions, the sole metal complex observed was identified as the dimeric species [(PPP)CoH] 2 suggesting that the catalytically active species may be a cobalt hydride monomer.