Unprecedented Reactivity of the Bridged Borylene Complexes [μ-BCl{(η5-C5H4Me)Mn(CO)2}2] toward Pyridine

The reactivity of the bridged chloroborylene complex [μ-BCl{(η5-C5H4Me)Mn(CO)2}2] (1) toward pyridine was investigated under various conditions. In the presence of protic reagents such as H[Co(CO)4] or H[BF4], the formation of the aminoborylene complex [1-(μ-B)-4-H-(NC5H5){(C5H4Me)Mn(CO)2}2] (2) was observed. Compound 2 represents the product of an unprecedented formal 1,4-hydroboration of pyridine. Corresponding reactions of 1 with pyridine and Tl[PF6] afforded 2 in similar yields, thus providing evidence that the abstraction of the boron bound chloride initiates the observed reaction. Complex 2 was fully characterized in solution and in the crystal.