PREPARATION OF THE TECHNETIUM(VI) AQUANITRIDO COMPLEXES (NET4)[TCNX4(OH2)] (X = CL OR BR) - CRYSTAL-STRUCTURES OF (NET4)[TCNBR4(OH2)] AND CS2[TCNCL5]

Addition of NEt4X to a conc. HX solution of [TcNX4(OH2)]- (X = Cl or Br) yields crystals of (NEt4)[TcNX4(OH2)] (X = Cl (1) or Br (2)). Complex 2 crystallises in the orthorhombic space group Pnma with a = 11.366(1), b = 12.930(2), c = 11.540(1) angstrom and Z = 4. Refinement with 1434 data measured with Cu K-alpha radiation converged with R = 0.047. The complex anion has distorted octahedral geometry with a water molecule trans to the nitrido ligand (Tc = N 1.599(9) and Tc-OH2 2.443(7) angstrom). Crystals of Cs2[TcNCl5] (3) belong to the cubic space group Fm3BARm with a = 10.211(1) angstrom and Z = 4. The ligands of the complex anion are statistically disordered over six octahedral sites as required by the cubic space group. Refinement based on 78 data measured with Cu K-alpha radiation, and with a fixed Tc = N distance of 1.6 angstrom, converged with R = 0.034. In this model Tc is displaced 0.401(3) angstrom from the plane of the cis ligands towards the nitrido ligand with Tc-Cl(cis) = 2.373(5), Tc-Cl(trans) = 2.740(5) angstrom.