An unprecedented family of luminescent iridium(III) complexes bearing a six-membered chelated tridentate C^N^C ligand

Abstract

A new family consisting of three luminescent neutral Ir(III) complexes with the unprecedented [Ir(C^N^C)(N^N)Cl] architecture, where C^N^C is a bis(six-membered) chelating tridentate tripod ligand derived from 2-benzhydrylpyridine (bnpy) and N^N is 4,4'-ditert-butyl-2,2'-bipyridine (dtBubpy) is reported. X-ray crystallography reveals an unexpected and unusual double C-H bond activation of the two distal non-conjugated phenyl rings of the bnpy coupled with a very short Ir-Cl bond trans to the pyridine of the bnpy ligand. Depending on the substitution on the bnpy ligand, phosphorescence, ranging from yellow to red, is observed in dichloromethane solution. A combined study of density functional theory (DFT) and time-dependent DFT (TD-DFT) corroborates the mixed charge-transfer nature of the related excited-states.