Reaction of Li2C2B10Me8H2 with NiCl2. Ligand effects on stability of Ni-octamethylcarboryne complexes

In the interaction of 1,2-Li2-4,5,7,8,9,10,11,12-Me8-1,2-C2B10H2 with NiCl2L2, phosphine ligands played an important role in the formation of different kinds of products. An expected Ni-carboryne complex (η2-C2B10Me8H2)Ni(PMe3)2, an unprecedented dinuclear Ni-carboryne species (η2-C2B10Me8H2)Ni(μ-σ:σ:η2-dppen)Ni(dppe) (dppe = 1,2-bis(diphenylphosphino)ethane, dppen = 1,2-bis(diphenylphosphino)ethene) and a tri-coordinate Ni(I)-carboranyl complex (σ-C2B10Me8H3)Ni(PPh3)2 were obtained using PMe3, dppe and PPh3 as ligand, respectively. The electron-deficient octamethylcarboryne over carboryne may contribute to the low stability of the corresponding Ni-carboryne complexes. All new complexes were spectroscopically characterized and their structures were confirmed by single-crystal X-ray analyses.