SYNTHESIS OF TECHNETIUM(V)-NITRIDO COMPLEXES WITH CHELATING AMINES - A NOVEL CLASS OF MONOCATIONIC, OCTAHEDRAL COMPLEXES CONTAINING THE [TC=N]2+ CORE - CRYSTAL-STRUCTURES OF [TCN(EN)2CL]+ (EN = ETHYLENEDIAMINE) AND [TCN(TAD)CL]+ (TAD = 1,5,8,12-TETRAAZADODECANE)

A novel class of monocationic complexes containing the [Tc≡N]2+ functional moiety is reported. The complexes are prepared by substitution reactions on the starting compound TcNCl2(PPh3)2 with neutral, bidentate, and tetradentate chelating amines or by reduction with KBH4 of the complex [TcNCl4]− in the presence of the same ligands. The complexes have been characterized by elemental analyses, IR and 1H NMR spectroscopy, conductivity, and magnetic susceptibility measurements. All the complexes possess a distorted octahedral geometry and, thus, constitute the first homogeneous class of stable, octahedral technetium(V)-nitrido complexes having a sixth, charged ligand in a position trans to the Tc≡N multiple bond. The crystal structures of two members of this class, namely the complexes [TcN(en)2Cl]+ (1) (en = ethylenediamine) and [TcN(tad)Cl]+ (2) (tad = 1,5,8,12-tetraazadodecane), have been determined. The complexes have a distorted octahedral structure, with a Cl− atom in a position trans to the Tc≡N group and two bidentate en ligands in 1 or one tetradentate tad ligand in 2 in the plane normal to the N≡Tc—Cl axis. Compound 1 crystallizes in the space group P21/n, with a = 9.316 (1) Å, b = 12.404 (1) Å, c = 24.367 (5) Å, β = 93.76(1)°, and V = 2809.7 (7) Å3 with Z = 4, for 4565 observed reflections with I ≥ 3σ(I); the Tc≡N bond length is 1.603 (3) Å, while the length of the Tc—Cl bond trans to Tc≡N is 2.7320 (8) Å, which is the longest Tc—Cl bond distance ever observed in technetium chemistry. Compound 2 crystallizes in space group Pna21 with a = 9.966 (2) Å, b = 31.203 (10) Å, c = 9.706 (4) Å, and V = 3018 (2) Å3 with Z = 4, for 2991 observed reflections with I ≥ 3σ(I); the Tc≡N bond length is 1.626 (6) Å, while the length of the Tc—Cl bond trans to Tc≡N is 2.663 (2) Å. © 1990, American Chemical Society. All rights reserved.