COORDINATION-COMPOUNDS OF THE LIGAND 1,6-BIS(3,5-DIMETHYL-1-PYRAZOLYL)-2,5-DITHIAHEXANE (BDDH) WITH DIVALENT NICKEL, COBALT AND ZINC SALTS - X-RAY CRYSTAL-STRUCTURE OF CO(BDDH)(NCS)2

The N2S2 ligand 1,6-bis(3,5-dimethyl-1-pyrazolyl)-2,5-dithiahexane (abbreviated bddh) forms the coordination compounds (Co, Ni, Zn)(bddh)Cl2, (Ni, Co)(bddh)(NCS)2 and [Ni(bddh)(NO3)2](H2O)2. The X-ray crystal structure of Co(bddh)(NCS)2 was determined at room temperature: tetragonal, space group P4(1)2(1)2, a = b = 9.083(1), c = 26.447(3) angstrom, alpha = beta = gamma = 90.0-degrees, Z = 4. The structure was solved by Patterson methods and refined by least-squares calculations to the residual R values of 0.038 (R) and 0.021 (R(w)) and the goodness-of-fit of 2.27 for 4808 measured, 2313 independent and 1999 observed (F > 4.0-sigma(F)) reflections. The cobalt(II) ion is in a distorted octahedral CoN2N'2S2 geometry, in agreement with its ligand field spectrum. The ligand chelates through two pyrazole N atoms in trans position and the two sulfur atoms in cis position. The thiocyanate anions coordinate through the N atoms in a cis position. The Co-donor distances are 2.119(2) (N-pyrazole), 2.579(1) (S) and 2.026(3) (N-thiocyanate) angstrom. The ligand field spectra of the nickel compounds agree with octahedral coordination of the metal ion. IR spectroscopy of [Ni(bddh)(NO3)2](H2O)2 Strongly suggests that both nitrate anions are monodentate and the water molecules are present in the crystal lattice. The compounds (Co, Zn)(bddh)Cl2 are X-ray isomorphous and the ligand field spectrum of Co(bddh)Cl2 shows a CoN2Cl2 chromophore.