Half-sandwich Ru(II), Ir(III) and Rh(III) complexes with bridging or chelating N-heterocyclic bis-carbene ligand: Synthesis and characterization

N-heterocyclic bis-carbene ligand (bis-NHC) which was derived from 1,1′-diisopropyl-3,3′-ethylenediimidazolium dibromide (L·2HBr) via silver carbene transfer method, reacted with [(η6-p-cymene)RuCl2]2 and [Cp∗MCl2]2 (Cp∗ = η5-C5Me5, M = Ir, Rh) respectively, afforded complexes [(η6-p-cymene)RuCl2]2(L) (1), [Cp∗IrCl2]2(L) (2) and [Cp∗RhCl(L)][Cp∗RhCl3] (3). When [Cp∗IrCl2]2 was treated with 2 equiv AgOTf at first, and then reacted with bis-NHC ligand, [Cp∗IrCl(L)]OTf (4) was obtained. The molecular structures of complexes 1–4 were determined by X-ray single crystal analysis, showing that 1 and 2 adopted bridging coordination mode, 3 and 4 adopted chelating coordination mode. All of these complexes were characterized by 1H, 13C NMR spectroscopy and element analysis.