Ru(II)-M(I) (M = Rh and Ir) bimetallic complexes based on a bridging ligand composed of 1,10-phenanthroline and N-heterocyclic carbene: Coordination chemistry and detection property of carbon monoxide

A series of mono-Ru-II and di-nuclear complexes, [Ru-II-M-I(COD)Cl and Ru-II-M-I(CO)(2)Cl] (M = Ir, Rh), have been prepared by using a bridging ligand, 1,3-dibutyl-2,3-dihydro-1H-imidazo[4,5-f][1,10] phenanthroline-2-yl (IL). This bridging ligand consists of 1,10-phenanthroline and N-heterocyclic carbene (NHC) and has two coordinating sites which can bind two different metals. The complexes synthesized have been fully characterized by H-1 NMR, C-13 NMR, high resolution mass spectrometry (HRMS), elemental analysis, and X-ray crystallography in one case. These complexes exhibited typical pi-pi* and metal-to-ligand charge transfer (MLCT) bands in the UV and visible regions, respectively. Compounds Ru-II-Ir-I (CO)(2)Cl and Ru-II-Rh-I(CO)(2)Cl have the stronger emission intensities and the longer luminescence lifetimes (tau) than those of RuII-IrI(COD) Cl and Ru-II-Rh-I(COD)Cl, respectively. Complex Ru-II-Ir-I(COD)Cl was applied to detect carbon monoxide. (C) 2012 Elsevier B.V. All rights reserved.