dppm and hydrido-bridged dinuclear complexes of iridium. Synthesis and structures of [(IrCp*)2(μ-dppm)(μ-H)(μ-X)]2+ (X = Cl, OMe, OH, or H)

Abstract

Reaction of [IrCp*Cl(μ-H)]₂1 (Cp* = pentamethylcyclopentadienyl) with two equivalents of bis(diphenylphosphino)methane (dppm) gave an unidentate dppm complex IrCp*(H)(Cl)(dppm-P) 2. This reacted with a half equivalent of [IrCp*Cl(μ-Cl)]₂3 to give a dppm-bridged dinuclear complex (Cl)(H)Cp*Ir(μ-dppm)IrCp*Cl₂4, in which the two metal centers are distal. Reaction of 4 with two equivalents of AgOTf (OTf = O₃SCF₃) gave a dppm, hydride and chloride-bridged diiridium complex [(IrCp*)₂(μ-dppm)(μ-H)(μ-Cl)][OTf]₂5a. Complex 5a reacted with sodium methoxide in methanol to give [(IrCp*)₂(μ-dppm)(μ-H)(μ-OMe)][OTf]₂6a. This reacted with water in refluxing acetone to give a diiridium complex [(IrCp*)₂(μ-dppm)(μ-H)(μ-OH)][OTf]₂7a. Heating complex 6a in refluxing toluene gave [(IrCp*)₂(μ-dppm)(μ-H)₂][OTf]₂8a. The structures of the anion exchanged complexes [(IrCp*)₂(μ-dppm)(μ-H)(μ-X)][BPh₄]₂ [X = Cl 5b, OMe 6b, OH 7b or H 8b] have been confirmed by X-ray analysis.