THE SYNTHESIS AND CHARACTERIZATION OF A TECHNETIUM(III) ISODIAZENE COMPLEX - THE X-RAY CRYSTAL-STRUCTURE OF [TCCL3(N=NPB2)(PPH3)(2)]

The reaction of the Tc(V) complex (Bu4N)[TcOCl4] with excess Ph2NNH2 . HCl and PPh3 in refluxing MeOH yields [TcCl3(N=NPh2)(PPh3)(2)]. The I R spectrum of the crystalline product shows a medium intensity band at 1092 cm(-1), which is assigned to nu(Tc=N) from the isodiazene core. The FAB(+) mass spectrum shows the protonated parent ion of 914 m/z an d the peak associated with the loss of a chloride from the parent ion of 878 m/z. The octahedral, Tc(III) complex is paramagnetic, with no s ignals observed in the H-1 NMR spectrum. The X-ray crystal structure s hows the mutually trans triphenyl-phosphine ligands with the isodiazen e and chloride ligands in the equatorial plane. The Tc-N bond length i s 1.738(4) Angstrom while the N-N bond is 1.300(5) Angstrom, which is consistent with the multiple bonding expected for the linearly bonded isodiazene ligand. The Tc-N-N bond angle of 175.6(3)degrees reflects t he sp hybridization of the isodiazene-alpha-nitrogen atom. The coordin ation geometry of this complex is a distorted octahedron. Crystal data for C50H44Cl7N2P2Tc: monoclinic space group P2(1)/n, a = 10.1294(1), b = 26.0792(3), c = 18.8147(3) Angstrom, beta = 98.814(1)degrees, V = 4911.52(11) Angstrom(3), with D-calc = 1.462 g cm(-3). Structure solut ion based on 6962 unique reflections converged at R = 0.0513, for (I > 2 sigma(I)); GOF = 1.33. (C) 1998 Elsevier Science S.A.