Influence of ligand donor-acceptor properties on the structure, optical, and electrochemical characteristics of Ir(III) complexes with cyclometallated 2-phenylbenzotiazole

The cis-C,C-structure of a series of cyclometallated Ir(III) complexes with 2-phenylbenzotiazole was determined by the methods of X-ray diffraction (XRD) analysis, H-1, C-13, P-31 NMR, and IR spectroscopy. Long-wave absorption bands, phosphorescence, and processes of electrochemical oxidation and reduction of the complexes were assigned to the transfer of electrons presumably located on d (pi) and pi* orbitals of cyclometallated 2-phenylbenzotiazole. The decrease in donor and acceptor properties of the ligands leads to the blue shift of absorption spectra and phosphorescence and to the anodic shift of oxidation and reduction potentials of the complexes.