Three-centre, two-electron bonds in complexes of Mn, Ni, Co and Cd with 3-(4-benzonitrile)pyrazolyl scorpionates

A series of complexes of the form [M(Bp3(4Bz))(Tp3(4Bz))] containing a mixture of novel dihydrobis(3-(4-benzonitrile)pyrazolyl)borato (Bp3(4Bz)) and hydrotris(3-(4-benzonitrile)pyrazolyl)borato (Tp3(4Bz)) ligands have been synthesised and structurally characterised. The ligands, both containing 3-(4-benzonitrile)pyrazole arms, form isostructural complexes with a variety of transition metals although different crystalline solvates have been obtained depending upon the crystallisation conditions, namely [M(Bp3(4Bz))(Tp3(4Bz))] (M = Ni, Co), [Ni((Bp3(4Bz))(Tp3(4Bz))]·2MeOH and [M(Bp3(4Bz))(Tp3(4Bz))]·MeOH (M = Mn, Cd). In all cases the metal atoms are five-coordinate with an additional agostic B–H interaction from the bis(pyrazolyl)borate ligand.