Heteroleptic Ni(II) Complexes Bearing a Bulky Yet Flexible IBiox-6 Ligand: Improved Selectivity in Cross-Electrophile Coupling of Benzyl Chlorides with Aryl Chlorides/Fluorides

A bisoxazoline-derived NHC known as IBiox-6 reacted smoothly with Ni[P(OEt)(3)](2)Br-2 and Ni(PPh3)(2)Br-2 to give the respective heteroleptic Ni(II) complexes Ni(IBiox-6)[P(OEt)(3)]Br-2 (1) and Ni(IBiox-6)(PPh3)Br-2 (2) in yields of 60% and 71%. Their crystal structures were characterized to reveal a rare cis disposition of the IBiox-6 ligand to the phosphite ligand in 1, while 2 possessed the more common trans configuration. Both complexes catalyzed the cross-electrophile coupling of benzyl chlorides with aryl chlorides and fluorides in the presence of Mg turnings at 50 degrees C via a real one-pot procedure, featuring no requirement for temperature variation or portionwise addition of any coupling partner. In particular, complex 1 showed a better balance between the catalytic activity and selectivity. The scope of the procedure catalyzed by 1 and Mg turnings was investigated, providing a highly selective, simple, and practical approach to the synthesis of diarylmethanes with high steric hindrance and various functional groups, including oligo-diarylmethane with asymmetric structures.