The C–H activation of pendant naphthyl group of 1-alkyl-2-(naphthyl-α-azo)imidazole by rhodium(III). Spectral, structural characterization and, DFT computation

The reaction of RhCl3 with 1-alkyl-2-(naphthyl-α-azo)imidazole (α-NaiR, N, N′chelator) (R = CH3, CH2–CH3, CH2–Ph) has synthesized a coordination compound, [Rh(α-NaiR-N, N′)(PPh3)Cl3] (2) from boiling methanol in the presence of PPh3 while the reaction under similar condition in the presence of Et3N has synthesized cyclometallated complex, [Rh(α-NaiR-N, N′, C)(PPh3)Cl2] (3). The structures of both types of complexes are confirmed by single crystal X-ray diffraction study in representative cases. All the complexes have been characterized by spectral data (FT-IR, UV–VIS, MS, 1H-NMR) and elemental analyses. Density functional theory calculation has also been performed to rationalize the electronic structures and their spectral properties.

Graphical abstractRh(III) complexes of 1-alkyl-2-(naphthyl-α-azo)imidazole (α-NaiR) present in coordination and cyclometallation states. The structures are described by spectroscopic (IR, UV–Vis, NMR, Mass) and single crystal X-ray diffraction studies. Density functional theory calculation has also been performed to rationalize the electronic structures and their spectral properties.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Rh(III) coordination and cyclometallated complexes of naphthylazoimidazoles. ► The X-ray structures establish the structures. ► The coordination complexes are transformed to cyclometallation derivatives. ► DFT computations have been used to interpret the electronic transitions.