Bidentate aryldichalcogenide complexes of [(diphosphino)ferrocene]palladium(II) and [(diphosphino)ferrocene]platinum(II). Synthesis, molecular structures and electrochemistry

A series of homochalcogenide and mixed-chalcogenide ligand complexes of palladium and platinum have been prepared from the reactions of Pd(dppf)Cl-2, (dppf= 1,1'-bis(diphenylphosphino)ferrocene), Pd(dippf)Cl-2 (1, 1'-bis(diisopropylphosphino)ferrocene), and Pt(dppf)Ch with 1,2-benzenedithiol (HSC6H4SH) (a), 3,4-toluenedithiol (HSC6H3MeSH) (b), 3,6-dichloro-1,2-benzenedithiol (HSC6H2Cl2SH) (c), 2-mercaptophenol (HSC6H4OH) (d), thiosalicylic acid (HSC6H4CO2H) (e) and thionicotinic acid (HSC6H3NCO2H) (f). Single-crystal X-ray diffraction studies show that all complexes have distorted square-planar geometry. The complexes undergo two quasi-reversible or irreversible one-electron redox processes that involve the chalcogen ligands and diphosphinoferrocene ligands. The oxidation potentials of the chalcogen ligands increase when they bear electron-withdrawing substituents. (C) 2001 Elsevier Science Ltd. All rights reserved.