ELECTRON-SPIN-RESONANCE STUDIES OF THE OXIDATION OF [TC(V)NCL2(EPH3)2] (E = P OR AS) TO [TC(VI)NCL4]- BY THIONYL CHLORIDE - STRUCTURE OF DICHLORONITRIDOBIS(TRIPHENYLARSINE)-TECHNETIUM(V)

The complexes [Tc(V)NCl2(EPh3)2] (E = P or As) are oxidized to [Tc(VI)NCl4]- in thionyl chloride solution at room temperature. ESR spectroscopy has established the presence of technetium(VI) intermediates, [TcNCl3(EPh3)]: E = P, g parallel-to = 2.0316, g perpendicular-to = 2.0026, A parallel-to = 0.0267 cm-1, A perpendicular-to = 0.0119 cm-1, Q = 0.000 35 cm-1, a(x) = a(y) = 0.0017 cm-1, a(z) = 0.00185 cm-1; E = As, g parallel-to = 2.0246, g perpendicular-to = 1.9986, A parallel-to = 0.0271 cm-1, A perpendicular-to 0.0125 cm-1, Q = 0.0003 cm-1, a(x) = a(y) = 0.00195 cm-1 and a(z) = 0.0021 cm-1. The crystal structure of [TcNCl2(AsPh3)2] 1 has been determined and is compared with those of Re(V)N and Tc(V)N phosphine complexes. Crystals of 1 are monoclinic, space group 12/a, with a = 15.823(4), b = 9.638(2), c = 22.490(7) angstrom, beta = 101.91(2)-degrees and Z = 4. Molecules of 1 possess C2 symmetry with N = Tc-Cl and N = Tc-As angles of 110.51 (3) and 99.22(1)-degrees, respectively. The Tc = N bond length is 1.601 (5) angstrom.