Thioloato-technetium complexes. 1. Synthesis and characterization of bis(tertiary diphosphine)technetium(III) complexes containing methanethiolato ligands. Single-crystal structural analyses of trans-[TcIII(SCH3)2(DMPE)2]CF3SO3 and trans-[TcIII(SCH3)2(DEPE)2]PF6, where DMPE = 1,2-bis(dimethylphosphino)ethane and DEPE = 1,2-bis(diethylphosphino)ethane

Abstract

The Tc(III) methanethiolato complexes trans-(Tc(SCH/sub 3/)/sub 2/D/sub 2/)/sup +/, where D is either 1,2-bis(dimethylphosphino)ethane (DMPE) or 1,2-bis(diethylphosphino)ethane (DEPE), have been synthesized and characterized. Preparation of these complexes from (Tc/sup V/(O)(OH)D/sub 2/)/sup 2+/ utilizes excess NaSCH/sub 3/ as reductant and ligand. The x-ray crystal structures of both title complexes are examined, and the crystal parameters are reported. In both structures the Tc atom occupies an inversion center. The visible spectra of these trans-(Tc(SCH/sub 3/)/sub 2/D/sub 2/)/sup +/ complexes in acetonitrile show sulfur-technetium charge-transfer bands at 16,810 and 28,490 cm/sup /minus/1/ for D = DMPE and at 16,610 and 28,830 cm/sup /minus/1/ for D = DEPE. Cyclic voltammetric measurements in N,N-dimethylformamide show two reversible reduction couples corresponding to Tc(III/II) and Tc(II/I) at -0.550 and -1.72 V vs Ag/AgCl for D = DMPE and -0.554 and -1.81 V vs Ag/AgCl for D = DEPE. The absorption spectra and cyclic voltammograms are compared with those of other trans-(TcD/sub 2/X/sub 2/)/sup +/ complexes with X = Cl, Br, -NCS and are discussed in terms of the relative strengths of the /simga/ and /pi/ interactions between Tc and the ligating S and P atoms. 45 refs., 5 figs., 8 tabs.