Nitrido-technetium and -rhenium Complexes with Chelating Phosphines: Synthesis, Reactivity and Crystal Structures

Article abstract of DOI:10.1039/DT9930001281

Nitrido-technetium(V) and -rhenium(V) complexes of general formula 1), 1,8-bis(diphenylphosphino)-3,6-dioxaoctane (L²) or 1,1,1-tris(diphenylphosphinomethyl)ethane (L³)> have been synthesized and characterized.They were prepared by the reduction of VINCl4>(1-) or by the replacement of the two triphenylphosphines of (M = Re or Tc) by bidentate or tripodal polyphosphine ligands L.Reaction of these complexes with an excess of potassium O-ethyl dithiocarbonate yields neutral dithiocarbonate compounds , while cationic and neutral complexes (1+) and were obtained upon reaction with K(S2CNEt2).The crystal structures of 1> and 2> have been determined by X-ray crystallography; the complex 1> shows square-pyramidal coordination at technetium with the Tc atom displaced from the basal plane towards the N atom by 0.410 Angstroem.An unusual trigonal-bipyramidal geometry is observed for 2>.The Tc<*>N bond distances (1.60 Angstroem) in both complexes are indicative of a strong triple bond.