Synthesis, Characterization, and Physical Properties of Cyclometalated Iridium(III) Complexes with 2-Phenylthiophene or 2-Phenylfuran Ligands

Abstract

Tris-cyclometalated Ir(III) complexes bearing C∧S or C∧O ligands have been synthesized and characterized, and their redox behavior, absorption spectra, and luminescence properties are reported. The four Ir(C∧S)- and Ir(C∧O)-type complexes studied here are mer-Ir(dfppz)2(ptp), mer-Ir(ppy)2(ptp), mer-Ir(dfppz)2(pf), and mer-Ir(ppy)2(pf) [dfppz = 1-(2,4-difluorophenyl)pyrazole; ppy = 2-phenylpyridine; ptp = 2-phenylthiophene; pf = 2-phenylfuran]. While no C∧S or C∧O cyclometalation took place using conventional synthetic methods, transmetalation of the chloro-bridged dimeric iridium complexes [(dfppz)2Ir(μ-Cl)2(dfppz)2] and [(ppy)2Ir(μ-Cl)2(ppy)2] with the organozincs of 2-phenylthiophene or 2-phenylfuran afforded the four anticipated complexes in good yields. X-ray structural analyses on complexes Ir(dfppz)2(ptp) and Ir(dfppz)2(pf) were established to confirm their molecular structures. The Ir−C (ptp) (2.121(13) A) and Ir−C (pf) (2.08(3) A) bonds are much longer than the other two Ir−C (dfppz) bonds in thei...