Arylazoimidazoles (RaaiH,p-R-C6H4N=N-C3H3N2, R=H, Me, OMe, Cl and NO2) are N,N′-chelators. On reaction with (NH4)2[OsCl6], two classes of isomers blue-violetctc-Os(RaaiH)2Cl2 and red-violetccc-Os(RaaiH)2Cl2 have been isolated. The complexes have been characterised by elemental analyses, IR, UV-Vis and1H NMR spectral data. The N=N stretching is red shifted by 70–80 cm−1 compared to the free ligand values and indicatesd(Os)→π*(azo) charge shifting. This is supported by MLCT transition in the visible region.1H NMR spectra suggest that blue-violet isomers areC2-symmetric and red-violet isomers areC1-symmetric. Redox studies show the Os(III)/(II) couple of both isomers at 0·6–0·7 Vvs SCE and two successive azo reductions.
Volume 134, 2022
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