Acid–Base Bifunction and Umpolung of the Bridging Hydride in a Coordinatively Unsaturated Mesylimido- and Hydrido-Bridged Diiridium Complex

The mono(mesylamido)-bridged diiridium(III) complex [(Cp*IrCl)2(μ2-H)(μ2-NHMs)] (Cp* = η5-C5(CH3)5, Ms = SO2CH3) undergoes reversible dehydrochlorination to afford the unsaturated imido-bridged dinuclear complex [Cp*Ir(μ2-H)(μ2-NMs)IrClCp*] (2). The reaction of 2 with trimethylphosphine gives the simple adduct [Cp*Ir{P(CH3)3}(μ2-H)(μ2-NMs)IrClCp*], while the reaction with CO results in sequential formation of the mono- and dicarbonyl Ir(II) complexes [Cp*Ir(CO)(μ2-NHMs)IrClCp*] and [{Cp*Ir(CO)}2(μ2-NMs)] with concomitant umpolung of the bridging hydrido ligand in 2 to the amido proton.