Rhodium(III) supported amination reaction of a pendant naphthyl group: Structure, electrochemistry and theoretical interpretation

Abstract

[Rh(α-NaiR)2Cl2]ClO4 (2) (α-NaiR (1), 1-alkyl-2-(naphthyl-α-azo)imidazoles, R = Me (a), Et (b)) complexes react with ArNH2 (where Ar = XC6H4, X = H (3), Me (4), Cl (5)) to synthesize the naphthyl appended CN fused bis-[1-alkyl-2-{(7-imidoaryl)naphthyl-α-azo}imidazole-N,N′,N″]rhodium(III)perchlorate complexes [Rh(α-NaiRNAr)2]ClO4 (3–5). The single crystal X-ray diffraction measurements of one of the complexes, [Rh(α-NaiEtNC6H5)2]ClO4 (3b), confirms the structure. The absorption spectra of the complexes 3–5 show high intense broad multiple transitions at 650–800 nm compared to the transition of the precursor 2 at 500 nm and DFT computations have assigned this transition to an admixture of LLCT (ligand-to-ligand charge transfer, imidoaryl → azonaphthyl) and LMCT transitions. The cyclic voltammogram shows a quasireversible oxidation at >0.8 V, which is assigned by DFT computation to oxidation of the imidoaryl chelate, along with azo reductions at <−0.4 V.