Photo- and Electroluminescent Neutral Iridium(III) Complexes Bearing Imidoylamidinate Ligands.

Imidoylamidinate-based heteroleptic bis(2-phenylbenzothiazole)iridium(III) and -rhodium(III) complexes [()M(NN)] ( = 2-phenylbenzothiazole, NN = '-(benzo[]thiazol-2-yl)acetimidamidyl ( and ), '-(6-fluorobenzo[]thiazol-2-yl)acetimidamidyl (), '-(benzo[]oxazol-2-yl)acetimidamidyl (), '-(1-methyl-1-benzo[]imidazol-2-yl)acetimidamidyl (); yields 70-84%) were obtained by the reaction of the in situ-generated solvento-complex [()M(NCMe)]NO and benzo[]thia/oxa/-methylimidozol-2-amines in the presence of NaOMe. Complexes - exhibited intense orange photoluminescence, reaching 37% at room temperature quantum yields, being immobilized in a poly(methyl methacrylate) matrix. A photophysical study of these species in a CHCl solution, neat powder, and frozen (77 K) MeOCHOH-EtOH glass matrix─along with density-functional theory (DFT), ab initio methods, and spin-orbit coupling time-dependent DFT calculations─verified the effects of substitution in the imidoylamidinate ligands on the excited-state properties. Electrochemical (cyclic voltammetry and differential pulse voltammetry) and theoretical DFT studies demonstrated noninnocent behavior of the imidoylamidinate ligands in - and complexes due to the significant contribution coming from these ligands in the HOMO of the complexes. The iridium(III) species exhibit a ligand (L, 2-phenylbenzothiazole)-centered (LC), metal-to-ligand (L', imidoylamidinate) charge-transfer (ML'CT,MLCT) character of their emission. The imidoylamidinate-based iridium(III) species were proved to be effective as the emissive dopant in an organic light-emitting diode device, fabricated in the framework of this study.