Hydride, borohydride, and dinitrogen pincer complexes of ruthenium

Reactions of chlorides RuCl(CO)(PCP) (1; PCP = [2,6-(CH2PBu2t)(2)C6H3](-)) and RuHCl[1,3-(CH2PBu2t)(2)C6H4] (2) with [Bu4N]BH4 in ethanol afforded the hydrides RuH(CO)(PCP) (3) and [RuH(PCP)](2)(mu-N-2) (5a), respectively. Complex 5a exists in equilibrium with the dinitrogen species [RuH(N-2)(PCP)](mu-N-2)[RuH(PCP)] (5b) and RuH(N-2)(PCP) (5c) in solution under N-2. Reaction of 1 and [Bu4N]BH4 in ether resulted in formation of the two isomeric borohydride complexes Ru(eta(2)-BH4)(CO)(PCP) (4a) and RuH(CO)[1-BH3-2,6-(CH2PBu2t)(2)C6H3].