Late 3<i>d</i>-Transition Metal Complexes Bearing a <i>Bis</i>-Phosphine Borane Ligand, PhB(CH₂P^<i>t</i>Bu₂)₂

The coordination chemistry of a bidentate ambiphilic ligand, PhB(CH2PtBu2)2 ([BP2tBu]), is established for a series of Co, Ni, and Cu compounds. The chloride starting materials [BP2tBu]MCl2 [M = Co (1Co), Ni (1Ni)] and [BP2tBu]CuCl (2Cu) are readily accessed in high yields by the treatment of the corresponding metal chloride salts with [BP2tBu] in THF solution. The reduction of 1Ni to [BP2tBu]NiCl (2Ni) was affected by treatment with KC8. In contrast, the corresponding CoI species was not isolable under similar reaction conditions. However, monovalent mesityl complexes of the form [BP2tBu]M(Mes) [M = Co (3Co), Ni (3Ni), Cu (3Cu)] were prepared by the treatment of 1Co with one equiv of Mes2Mg(THF)2 or by the reaction of 2M (M = Ni, Cu) with 0.5 equiv of Mes2Mg(THF)2. Modification of the borane moiety in 2Ni was explored by the treatment of this complex with 4-dimethylaminopyridine (DMAP) to produce [PhB(DMAP)(CH2PtBu2)2]NiCl (4), which displays distinct features in its UV–visible spectrum compared to 2Ni. The solid-state molecular structures of most complexes have been determined by single-crystal X-ray diffraction analysis.