The C–N coupling reaction of pendant naphthyl group of palladium(II) complexes of 1-alkyl-2-(naphthyl-β-azo)imidazoles. Structural characterization, spectral and redox properties, and correlation with DFT computed data

Abstract

The reaction of Pd(β-NaiR)Cl 2 ( 2) [β-NaiR ( 1) = 1-alkyl-2-(naphthyl-β-azo)imidazoles] with ArNH 2 in MeCN has yielded a C–N coupled product chloro[1-alkyl-2-{(7-imidoaryl)naphthyl-β-azo}imidazole-N,N′,N′′]palladium(II), Pd(β-NaiR–N–Ar)Cl ( 3– 5) and coupling takes place at ortho-C–H position of pendant naphthyl group. The structural confirmation has been achieved by single crystal X-ray structure determination of the representative complexes, Pd(β-NaiEt)Cl 2 ( 2b) and Pd(β-NaiEt–N–C 6H 4–Cl- p)Cl ( 5b). The electronic spectra of the products, 3– 5, exhibit characteristic transition within 600–900 nm those are absent in Pd(β-NaiR)Cl 2 ( 2). Cyclic voltammogram shows one oxidative response and two ligand reductions. The products are emissive. The excited state decays via radiative and non-radiative biexponential routes. The electronic structure, spectra and redox properties are explained by DFT computation.