Neutral and zwitterionic half-sandwich Ir, Rh complexes supported by P,S-substituted o-carboranyl ligands: Synthesis, characterization and reactivity

Abstract

The neutral Cp*M(Cl)(1-PPh₂-2-S-1,2-C₂B₁₀H₁₀) and zwitterionic Cp*M(3-OCH₃-7-PPh₂-8-S-7,8-C₂B₉H₉) (Cp* = η⁵-C₅Me₅, M = Ir, Rh, 1-PPh₂-2-S-1,2-C₂B₁₀H₁₀ = [1-(diphenylphosphino)-2-thiolato)-1,2-dicarba-closo-carborane], 3-OCH₃-7-PPh₂-8-S-7,8-C₂B₉H₉ = [3-(methoxyl)-7-(diphenylphosphino)-8-(thiolato)-7,8-dicarba-nido-carborane]⁻) were synthesized and fully characterized. The 18-electron neutral closo-carborane complexes Cp*M(Cl)(1-PPh₂-2-S-1,2-C₂B₁₀H₁₀) (M = Ir (1a), Rh (1b)) can be easily deboronated to result in the formation of reactive 16-electron zwitterionic nido-carborane complexes [Cp*M(3-OCH₃-7-PPh₂-8-S-7,8-C₂B₉H₉)] (M = Ir (2a), Rh(2b)). The oxidation of 2b with O₂ gas afforded the corresponding sulfone complex 3b in high yields. Utilization of its unsaturated feature in 16-electron zwitterionic nido-carborane complexes offers a potential strategy to synthesize new types of organometallic complexes.