Binuclear rhodium(III) and iridium(III) monoselenocarboxylates: Synthesis, spectroscopy and structure of an ortho-metallated iridium complex featuring an IrCCC(μ-Se) chelate ring

Monoselenocarboxylate–bridged binuclear complexes of RhIII and IrIII, [(Cp∗MCl)2(μ-SeCOAr)2] (1) (M = Rh or Ir; Cp∗ = pentamethylcyclopentadienyl; Ar = Ph, C6H4Me–4), have been isolated either by the reaction between [Cp∗2M2(μ-Cl)2Cl2] with KSeCOAr in acetonitrile or by treatment of [Cp∗MCl(solvent)2][PF6] with KSeCOAr in acetone. The novel binuclear complexes, [Cp∗IrCl(μ-SeCOAr)(κ2-SeCOC6H3R–)IrCp∗] (2) (R = H or Me-4) with ortho-metallation at one of the iridium centres have been isolated following the use of excess AgPF6. The single crystal structure of [Cp∗IrCl(μ-SeCOC6H5)(κ2-SeCOC6H4–)IrCp∗] (2a) exhibits two phenylcarboselenolate moieties situated in syn fashion with respect to the “Ir2Se2” plane, one of which leans towards the metal centre in order to undergo ortho-metallation after iridium–chlorine bond dissociation.