Synthesis and properties of pentachloro(ligand)iridate(IV) anions [IrLCl5]–(L = pyridine, PPh3, AsPh3, SbPh3, SMe2, SPh2, or SeMe2)

Abstract

Purple [NEt₄][Ir(py)Cl₅](py = pyridine) is conveniently obtained by reaction of trans-[Ir(py)₂Cl₄] with HCl gas and NEt₄Cl in CH₂Cl₂ solution. Reduction of this anion with ascorbic acid, followed by successive treatment with L (L = SMe₂, SeMe₂, PPh₃, AsPh₃, or SbPh₃), Cl₂, and HCl, afford [NEt₄][IrLCl₅], which have been characterised by analysis, i.r. and u.v.–visible spectroscopy, and conductance measurements. The potentials for the reductions were measured, and the formal potentials for the Ir^III–Ir^IV couples are compared with those of trans-[IrL₂Cl₄]^0/– and cis-[Ir(L–L)Cl₄]^0/–(L–L = bidentate ligand analogue of L).