Structural studies of technetium complexes. Part 4. The crystal structure of trans,trans-acetonitriledi-isothiocyanato(nitrido)bis-(triphenylphosphine)technetium(V)–acetonitrile (1/0.5)

Abstract

The title compound, [TcN(NCS)₂(CH₃CN)(PPh₃)₂]·0.5CH₃CN, has been prepared by substitution of [TcNCl₂(PPh₃)₂] with NH₄NCS followed by the reaction of the [TcN(NCS)₂(PPh₃)₂] complex with CH₃CN. The crystal structure of [TcN(NCS)₂(CH₃CN)(PPh₃)₂]·0.5CH₃CN has been determined by single-crystal X-ray diffraction methods at 25 ± 2 °C. Crystals are monoclinic, space group P2₁/c, with a= 9.296(3), b= 18.614(5), c= 23.307(6)Å, β= 109.63(2)°, and Z= 4. Diffractometry has provided significant Bragg intensities for 5 498 independent reflections and the structure has been refined by full-matrix least-squares methods to R= 0.045. The compound consists of discrete [TcN(NCS)₂(CH₃CN)(PPh₃)₂] molecules with CH₃CN of crystallisation also present in the crystal lattice. The technetium atom has a distorted octahedral environment with Tc–N–C angles of 177.1 (4) and 166.7(4)° for the NCS ligands and 168.6(4)° for the CH₃CN ligand. The TcN bond distance is 1.629(4)Å and the strong trans influence of the nitrido-group is evident in the exceptionally long Tc–N bond distance [2.491 (4)Å] to the CH₃CN ligand.