Synthesis and Luminescence of Cyclometalated Compounds with Nitrile and Isocyanide Ligands

Abstract

Mononuclear cationic cyclometalated palladium complexes [Pd(C∧N)(NCMe)2]ClO4 [C∧N = benzoquinolinate (bzq) 1, 2-phenylpyridinate (ppy) 2], analogous to the previously described platinum complexes [Pt(C∧N)(NCMe)2]ClO4 [C∧N = bzq 3, ppy 4], and the isocyanide platinum benzoquinolinate [Pt(bzq)(CNR)2]X (R = tert-butyl (t-Bu, 5), 2,6-dimethylphenyl (Xyl, 6), 2-naphthyl (2-Np, 7); X = ClO4− a, PF6− b) have been prepared and characterized. The solid-state structures of the cation [Pt(C∧N)(CN-Xyl)2]+ with different counteranions (6a and 6b) were found to be different in terms of packing, although in both cases they were dominated by π−π intermolecular interactions. The influence of the counteranion in the UV−vis spectra, both in solution and in the solid state of 5−7, is negligible. Time-dependent density-functional theory calculations on cation [Pt(C∧N)(CN-Xyl)2]+ (6+) have been performed, suggesting that the lowest absorption is 1IL in nature mixed with some 1MLCT character. Acetonitrile platinum complexes (3,...