Constrained-geometry ruthenium carboranyl complexes and their unique chemical properties

Abstract

By utilizing the unique electronic and steric properties of the icosahedral carboranyl moiety, a new class of constrained-geometry ruthenium complexes bearing linked cyclopentadienyl–carboranyl ligands has been achieved. They exhibit interesting reactivity patterns, of which some are different from conventional cyclopentadienyl ruthenium complexes. For example, the Cp in the constrained-geometry [η⁵:σ_C–Me₂C(C₅H₄)C₂B₁₀H₁₀]Ru systems is active and participates in reactions to give C–C coupling products whereas the “CpRu” moiety in CpRu–X is inert and remains intact in the same reactions. The constrained-geometry ligands can also stabilize mononuclear Ru bis(vinylidene) complexes and furnish the Ru–C(cage) to Ru–B(cage) conversion in the presence of H₂. This account provides an overview of our recent work in this area.