Ditopic Ambiphilicity of an Anionic Dimetalloborylene Complex

In early reports, the boron atom of the anionic borido
complexes
[{(η5-C5H4R)­(OC)2Mn}2B]− (R = H, Me) showed nucleophilic
behavior in the presence of electrophiles such as methyl iodide and
group 11 metal chlorides, akin to the ground-breaking boryl lithium
of Yamashita and Nozaki. Later, a reaction with the well-known transition
metal Lewis base [Pt­(PCy3)2] suggested the possibility
of boron-centered electrophilicity. In this paper we elucidate a third
reactivity profile of the anion, nucleophilic substitution on heavier
halides of group 14 metals by a manganese center. Meanwhile, other
group 11 halides were found to interact with the boron center, but
form structures different from those seen with gold. The basis of
the discrimination of the anion between main group and transition
metal halides is explored computationally, and the ditopic, ambiphilic
reactivity of the anions is discussed.