Pd(II) and Pt(II) Metallacycles with Unsymmetrical Ylide: Antiproliferative Effects and Application in Electrocatalytic Oxidation of Methanol

New Pd(II) and Pt(II) complexes are described in which the multidentate phosphorus ylides [Ph2P(CH2)(n)PPh2=C(H)C(O)C6H4-p-OCH3] (n=1, (Y1); n=2, (Y2)) act as P,C chelating ligands. The chelating ability of these ligands resulted in the formation of [MBr2{K-2(P,C)-Y1}] (M=Pd (1), Pt (2)); [MBr2{K-2(P,C)-Y2}] (M=Pd (3), Pt (4) complexes, which were investigated using physicochemical techniques. X-ray diffraction studies of a single crystal of complex 2 confirmed the structure of the five-membered ring. Owing to the redox activity of phosphorus-ylide complexes, their electrocatalytic activity for the oxidation of methanol has been studied. All compounds were found to possess the anti-proliferative potency against MCF-7 (breast carcinoma), A549 (non-small lung carcinoma) and AGS (gastric carcinoma) cell lines with average IC50 values in the range of 14.53 to 287.92 mu M. In general, the compounds Y1, Y2, 2, and 3 displayed high anticancer activities compared to 1 and 4. The antioxidant activity of the compounds, which was estimated by 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging, was moderate to strong with IC50 values in the range 0.18 to 0.59 mg mL(-1).