Nitrate/nitrite reductase activity of sulfido/selenido bridged dinuclear ruthenium(III) complexes

Series of dinuclear species [Ru-2(L)(2)(LH)(2)-mu -S2Cl2], [Ru-2(L)(2)(LH)( 4)-mu -Se2Cl2] (L=(LH)-H-1 and (LH)-H-3) and [Ru-2(L-2)(2) ((LH)-H-2)-mu -S e2Cl2]. 2H(2)O, where (LH)-H-1, (LH)-H-2 and (LH)-H-3 represent for 2-merca pto-5-phenyl-1,3,4-oxadiazole, 2-mercapto-benzimidazole and 2-mercaptobenzo thiazole, respectively, have been prepared and characterized by their eleme ntal analyses and spectral (IR, UV-visible, H-1 NMR and FAB mass) data. The diamagnetism of these complexes are indicative of an exchange coupled dinu clear ruthenium(III) species containing S-2(2-) and Se-2(2-) bridges. The c omplexes along with free heterocycles ((LH)-H-1-(LH)-H-3) as well as RuCl3. 3H(2)O were tested for their nitrate and nitrite reductase activities. The electrochemical behaviour of the complexes showed irreversible oxidation p eaks at +(1.04-1.40) V quite comparable to those reported for sulphido brid ged complexes. (C) 2001 Elsevier Science BY All rights reserved.