Reactions of [(dmpe)MnH(CH)]: synthesis and characterization of manganese(i) borohydride and hydride complexes.

Reactions of trans-[(dmpe)MnH(CH)] (1) with BH(NMe), 9-BBN, and HBMes yielded the manganese(i) borohydride complexes [(dmpe)Mn(μ-H)BR] (3: R = H, 4: R = CH, 5: R = Mes). The reaction of 1 with BH(NMe) proceeds via ethylene substitution. By contrast, a detuerium labelling study indicates that the reaction of 1 with HBMes involves initial isomerization of 1 to an unobserved 5-coordinate ethyl intermediate, [(dmpe)MnEt], which reacts with the hydroborane to afford EtBR and [(dmpe)MnH], followed by reaction with a second equivalent of hydroborane to generate 5 (an analogous pathway is likely followed for other base-free hydroboranes such as 9-BBN).