Synthesis, Structure, and Reactivity of Diazoketiminato Complexes of Platinum(II) and Palladium(II): Cytotoxic Properties of a Platinum Complex

Abstract

AbstractReaction 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)