SYNTHESIS AND CHARACTERIZATION OF THE THIOLATO RHENIUM(III) COMPLEXESCIS-[RE(SC6H4X-P)2(DMPE)2]PF6 AND TRANS-[RE(SC6H4X-P)2(DMPE)2]PF6, X = H, ME OR CL, DMPE = 1,2-BIS(DIMETHYLPHOSPHINO)ETHANE - SINGLE-CRYSTAL STRUCTURAL-ANALYSIS OF CIS-[RE(SPH)2(DMPE)2]PF6

The reaction of trans-[ReOC13(PPh3)2] with excess arenethiol and DMPE [1,2-bis(dimethylphosphino)ethane] produces both cis and trans isomers of the air stable arenethiolato-Re(III) complexes [Re(SC6H4X-p)2-(DMP E)2]+ (X = H, Me or Cl). These complexes have been characterized by FA B mass spectroscopy, u.v.-vis. spectroscopy, cyclic voltammetry and el emental analyses. The cis geometry of [Re(SPh)2(DMPE)2]+ is confirmed by X-ray crystallography. Averaged structural parameters are Re-S = 2. 293(4) angstrom, Re-P (trans to P) = 2.415(5) angstrom, Re-P (trans to S) = 2.486(6) angstrom, and Re-S-C = 118.5(5)-degrees. Cyclic voltamm etry measurements in DMF showed reversible Re(III)/Re(II) redox couple s in the - 0.43 V to - 0.53 V range for cis isomers and -0.48V to 0.60 V for trans isomers, both versus Ag/AgCl (3 M NaCl). Irreversible coup les were observed for Re(II)/Rc(I) and Re(IV)/Re(III). The relative pr edominance of cis and trans isomers in the synthesis of [Re(SR)2(DIP)2 ]+ and [Tc(SR)2(DIP)2]+ (DIP = diphosphine) complexes are discussed, a nd lead to the conclusion that the geometry is primarily determined by steric considerations.