Synthesis, structural characterization, and reactivity of late transition-metal complexes bearing linked cyclopentadienyl–carboranyl ligands

Abstract

Late transition-metal complexes bearing linked cyclopentadienyl/indenyl–carboranyl ligands were synthesized and their reactivities were examined. Reaction of Li2[Me2C(L)(C2B10H10)] (L = C5H4, C9H6, Me2NCH2CH2C5H3) with MCl2(PPh3)2 in Et2O afforded [η5:σ-Me2C(C5H4)(C2B10H10)]M(PPh3) (M = Co (4), Ni (5)), [η5:σ-Me2C(C9H6)(C2B10H10)]M(PPh3) (M = Co (6), Ni (7)), and [η5:σ-Me2C(Me2NCH2CH2C5H3)(C2B10H10)]Ni(PPh3) (8). Treatment of 4 or 5 with 2,6-dimethylphenylisocyanide, N-heterocyclic carbene (NHC), PCy3, or 1,2-bis(diphenylphosphino)ethane (dppe) gave the corresponding PPh3 displacement complexes [η5:σ-Me2C(C5H4)(C2B10H10)]M(2,6-Me2C6H3NC) (M = Co (9), Ni (10)), [η5:σ-Me2C(C5H4)(C2B10H10)]M[1,3-(2,6-i-Pr2C6H3)2C3N2H2] (M = Co (11), Ni (12)), [η5:σ-Me2C(C5H4)(C2B10H10)]Ni(PCy3) (13), or {[η5:σ-Me2C(C5H4)(C2B10H10)]Co}2(dppe) (14), respectively. These complexes were characterized by various spectroscopic techniques and elemental analyses. The molecular structures of 4–14 were further confirmed by single-crystal X-ray analyses.