• Tarun Kumar Misra

      Articles written in Journal of Chemical Sciences

    • Studies on the chemistry of copper(I) with arylazoimidazoles

      Tarun Kumar Misra Prasanta Kumar Santra Chittaranjan Sinha

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      N(1)-alkyl-2-(arylazo)imidazoles (RC6H4N=NC3H2N N(1)X; X=Me (a), Et (b); R=7-Me(L1), 7-OMe(L2), 7-Cl(L3), 7-NO2(L4) and 8-Me(L5)) yield perchlorate salts ofbis-chelated complexes with copper(I). The complexes are 1:1 electrolyte and the composition in supported by Jobs method of continuous variation. The N=N stretching is red shifted by 60–70 cm−1 compared to free ligand values suggesting efficient charge delocalization from Cu(I) to ligand centre. This is supported by high intense MLCT transitions in the visible region. The complexes show highly resolved symmetrical1H NMR spectra exhibiting C2-symmetry at least in the NMR time scale. In MeOH the complexes exhibit quasi-reversible CuL22+/CuL2+ couple at 0.4–0.5 Vvs SCE at 298 K. The high positive potential may be due to the distortion in the geometry of CuL2+.

    • Osmium arylazoimidazoles: Synthesis, spectral characterisation and redox properties of the complexes

      Sanjib Pal Tarun Kumar Misra Pabitra Chattopadhyay Chittaranjan Sinha

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      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.

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