Platinum(II) complexes with the tridentate phosphino–thioether ligand bis(2-diphenylphosphinoethyl)sulfide, (PPh2CH2CH2)2S. X-ray crystal structures of [Pt{(PPh2CH2CH2)2S}Cl]ClO4 and [Pt{(PPh2CH2CH2)2S}I]I

Abstract A series of new four coordinate Pt(II) complexes with the potentially tridentate chelate ligand bis(2-diphenylphosphinoethyl)sulfide (PSP) have been synthesized and characterized and the X-ray crystal stuctures of [Pt(PSP)Cl]ClO 4 and [Pt(PSP)I]I were determined. The spectroscopic data are consistent with the general formula [Pt(PSP)X] n + with X=Cl − , Br − , I − , SCN − , CN − , thiourea or PPh 3 where all the three donor atoms in PSP are coordinated to platinum in all the complexes. Both the crystal structures show that the coordination sphere of the tridentate chelate system is strongly tetrahedrally distorted from a square planar geometry. The larger iodide ligand appears to cause a greater distortion. The potentially larger trans influence of iodide shows no effect on the structure of the, apparently, rigid Pt(PSP) moiety, whereas the trans influence of the chelating sulfur donor appears to be large which is reflected in unusually long platinum–halogen distances.