The free ligands, 2-{(o-hydroxyaryl)azo}-1-N-salicylidene phenylamine, H(2)L [where H(2)L = RC(6)H(4)N=NC(6)H(4)N=CH-C(6)H(4)OHR = p-H for H(2)L(1), p-Me for H(2)L(2) and p-Cl for H(2)L(3)], were prepared by the condensation of salicylaldehyde with 2-{(o-hydroxy aryl)azo} aniline. Reaction of H(2)L with VOSO(4) afforded the oxovanadium complex, (L)V(O)(H(2)O). The (L(1))V(O)(H(2)O) complex displays two reversible responses at 0.7 V and -0.65 V vs. SCE in cyclic voltammetry. Catalytic activity of (L(1))V(O)(H(2)O) toward H(2)O(2) induced oxidation of organic thioethers to sulfoxide and sulfones have been examined. The cytotoxicity of (L(1))V(O)(H(2)O) has also been examined on human lung cancer cells.

The new ligands N- [2-(arylazo) 2-ligands bind Ni II in tetradentate (C,N,N,O) fashion in distorted square-planar geometry. Reaction of (L sal )Ni with meta-chloroperbenzoic acid, tert-butyl hydroperoxide, or hydrogen peroxide furnished

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Reaction of the 2‐(arylazo)anilines Ar‐N=N‐C6H4NH2 [HLnNH2; Ar = C6H5 (HL1), p‐CH3C6H4 (HL2), p‐ClC6H4 (HL3)] with K2PtCl4 in dmso affords the new PtII azoimine complexes [(HLnNH)Pt(dmso)Cl] where the chloride and dmso ligands are mutually cis. In contrast, treatment of Na2PdCl4 with HLnNH2 in dmso gives the chloro‐bridged palladium dimer [{(HLnNH)PdCl}2] as the major product along with [(HLnNH)2Pd] as the minor product. Further, the reaction of HLnNHCH2Ph with K2PtCl4 in dmso also gives [(HLnNH)Pt(dmso)Cl] whereas Na2PdCl4 affords the orthopalladated complexes [(LnNHCH2Ph)PdCl]. This means that the N–C(CH2Ph) bond is selectively cleaved by K2PtCl4. The reaction of [(HLnNH)Pt(dmso)Cl] with acetylacetone (acacH) gives the heteroleptic complex [(HLnNH)Pt(acac)]. [(HLnNH)Pt(dmso)Cl] and [(HLnNH)Pt(acac)] display a reversible reductive response at –1.20 and –1.46 V vs. SCE, respectively, in their cyclic voltammograms. The nature of the redox orbitals has been determined semi‐empirically employing the EHMO method. The cytotoxicity of [(HL1NH)Pt(dmso)Cl] has been examined with HeLa cells and the sub‐lethal dose (8 μM) determined by dose‐dependence studies. The relative degree of apoptotic and necrotic cell death using a sub‐lethal dose were measured by flow cytometry.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

which cyclic volatammograms exhibited one quasi-reversible oxidative response within the range 0.54-0.6 V vs SCE. The X-ray crystal structure of [OsBr(L 1 -NH)(CO)(PPh 3 ) 2 ] has been determined and its electronic structure was evaluated on the basis of single point DFT calculations using its crystallographic coordinates.

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