Synthetic, electrochemical, and structural studies on heterobimetallic crown thioether complexes with Group 10 metals: the crystal structures of [Pt(9S3)(dppf)](PF6)(2)center dot CH3NO2 and [Pd(9S3)(dppf)](PF6)(2)center dot CH3NO2

The syntheses, electrochemistry, and crystal structures for two new Pt(II) and Pd(II) heteroleptic bimetallic complexes with the crown trithioether 1, 4,7-trithiacyclononane (9S3) and the diphosphine ligand, 1,1'-bis(diphenylp hosphino)ferrocene (dppf) are reported. Both complexes have the general for mula [M(9S3)(dppf)](PF6)(2) (M = Pt or Pd) and exhibit the anticipated stru cture forming a distorted cis square planar array of two sulfur atoms from the 9S3 and two phosphorus atoms. These are, to our knowledge, the first re ported examples of dppf transition metal complexes involving a thioether as the ancillary ligand. The dppf ligand functions as a bidentate chelator to a single metal center, and the third 9S3 sulfur atom does interact with th e metal ion from a greater distance (Pt-S = 2.8167(8) Angstrom; Pd-S = 2.79 16(5) Angstrom) to yield an elongated square pyramidal geometry. The two st ructures are isomorphous with very similar bond distances and angles, The v alues for the P-31-NMR chemical shifts (Pt = 15.09 ppm, Pd = - 0.47 ppm), t he Pt-195-NMR chemical shift for the Pt(II) complex ( -4353 ppm) and (1)J(P t-195-P-31) Coupling constants (3511 Hz) are all consistent with a cis-MS2P 2 square planar coordination sphere. The 9S3 ligand is fluxional in solutio n for both complexes. The electrochemistry of both complexes is dominated b y a reversible Fe(II)/Fe(III) couple from the ferrocene moiety (E-1/2 = + 7 21 mV for Pt(II), + 732 mV for Pd(II), both versus Fc/Fc(+)). (C) 2001 Else vier Science B.V. All rights reserved.