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8343875 
Journal Article 
Review 
Bimetallic N-heterocyclic carbene-iridium complexes: investigating metal-metal and metal-ligand communication via electrochemistry and phosphorescence spectroscopy 
Tennyson, AG; Rosen, EL; Collins, MS; Lynch, VM; Bielawski, CW 
2009 
Yes 
Inorganic Chemistry
ISSN: 0020-1669
EISSN: 1520-510X 
AMER CHEMICAL SOC 
WASHINGTON 
48 
14 
6924-6933 
English 
19537803 
WOS:000268137900074 
Bimetallic [Ir(COD)Cl] and [Ir(ppy)(2)] (COD = 1,5-cyclooctadiene; ppy = 2-phenylpyridyl) complexes bridged by 1,7-dimethyl-3,5-diphenylbenzobis(imidazolylidene) (1), in addition to their monometallic analogues supported by 1-methyl-3-phenylbenzimidazolylidene (2), were synthesized and studied. Electrochemical analyses indicated that 1 facilitated moderate electronic coupling between [Ir(COD)Cl] units (DeltaE = approximately 60 mV), but not [Ir(ppy)(2)]. The metal-based oxidation potentials for the bimetallic complexes were within 20 mV of those for their monometallic analogues. Furthermore, spectroscopic analyses of the [Ir(ppy)(2)] bimetallic and monometallic complexes revealed nearly identical phosphorescence profiles, indicating that carbene coordination does not affect the energy of the emissive states. Collectively, these results suggest that N-heterocyclic carbenes (NHCs) such as 1 could link together two emissive fragments without altering their fundamental phosphorescence profiles. Ultimately, employing multitopic NHCs as non-interfering molecular connectors could facilitate the rational design of new phosphorescent materials as well as second-generation phosphor dopants.