Formal Nickelate(−I) Complexes Supported by Group 13 Ions

Formal nickelate(−I) complexes bearing Group 13 metalloligands (M=Al and Ga) were isolated. These 17 e⁻ complexes were synthesized by one-electron reduction of the corresponding Ni⁰→M^III precursors, and were investigated by single-crystal X-ray diffraction, EPR spectroscopy, and quantum chemical calculations. Collectively, the experimental and computational data support: 1) the strengthening of the Ni−M bond upon one-electron reduction, and 2) the delocalization of the unpaired spin across the Ni and M atoms. An intriguing electronic configuration is revealed where three valence electrons occupy two σ-type bonding interactions: Ni(3d (Formula presented.))²→M and σ-(Ni−M)¹. The latter is an unusual Ni−M σ-bonding molecular orbital that comprises primarily the Ni 4p_z and M np_z/ns atomic orbitals.