• R Mishra

      Articles written in Journal of Chemical Sciences

    • Closed shell-closed shell S, S-bridged heteropolymetallic aggregates: Synthesis and characterisation

      R G Bhattacharyya R Mishra

      More Details Abstract Fulltext PDF

      [Cu(CN)x]1−x in the presence of excess of KCN reacts with MS42− and M02S22− (M = W, Mo) producing [NC−CuS2MS2]2− and hitherto unknown [NC−CuS2−M02]2− respectively as PPh4 salts. Complexes have been characterised by typicalvCN,v(M=S), v(M-S-M′) andv(M=0) vibrations in appropriate cases. In their electronic spectra the intraligand (MS42− or M02S22−) transitions are interestingly perturbed. Cd2+ affords [Cd(WS4)2]2− and [Cd(W02S2)2]2− but Hg2+ is reduced by WS42− and W02S22−affording [S2WS2HgHgS2WS2]2− and [02WS2HgHgS2W02]2− respectively. Besides LMCT transitions, the softer Cd and Hg complexes presumably also show MLCT type transitions. Pb2+ affords [Pb2[WS4)4]4− which is isostructural with the Sn-analogue. The copper-tungsten complexes show irreversible reduction waves in their cyclic voltammograms, indicating the reduction of W(VI) to W(V). The corresponding Mo complexes show quasi-reversibility whereby Mo(VI) is reduced to Mo(V) and then MoS43− is reversibly oxidised. The Hg(I) centres in the mercury complexes are also reduced to Hg(0). [NC−CuS2WS2]2− reacts with NiCl2·6H20 probably forming [CuS2WS2NiS2WS2Cu]2− and [NC−CuS2W02]2− reacts with UO22+ presumably affording [NCCuS2W02U02(H20)02·WS2 CuCN]2− providing evidence that besides the W=S bond, the W=0 bond can also show nucleophilic character.

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