COORDINATION-COMPOUNDS WITH THE N2S DONOR LIGAND 1,3-BIS(5'-METHYL-4'-IMIDAZOLYL)-2-THIAPROPANE (SBI) - THE X-RAY STRUCTURE OF [ZNCL2(SBI)]

The synthesis, spectroscopy and structure of mononuclear transition-metal coordination compounds of the ligand 1,3-bis(5'-methyl-4'-imidazolyl)-2-thiapropane (sbi) are described. The ligand acts as a didentate N2-ligand in the compounds [ZnBr2(sbi)], [ZnCl2(sbi)] and [CoCl2(sbi)], and the anions take part in the coordination of the metal ion, resulting in tetrahedral geometries with N2X2 chromophores. The ligand acts as a tridentate ligand in the compounds [M(sbi)2]X2(H2O)n with M = Co2+, Ni2+; X = Cl-, NO3-, BF4-; n = 0-4; and [Co(sbi)2](BF4)3, resulting in octahedral geometries with an N4S2 chromophore. The latter compound formed by spontanious oxidation from a Co(II) solution. The compound [ZnCl2(sbi)] crystallizes in the triclinic space group P1BAR with a = 8.357(2), b = 8.935(3), c = 10.600(3) angstrom, alpha = 75.25(2), beta = 83.45(2), gamma = 75.15(2)degrees, V = 738.9 angstrom3, Z = 2. The structure was solved with the Patterson map and refined by full-matrix least-squares methods to a residual R of 0.035 (R(w) = 0.041) for 2824 significant reflections. The Zn(II) ion is tetrahedrally surrounded by two imidazole nitrogens of the ligand sbi and two chloride ions, with distances of 2.012(2), 2.019(2), 2.243(1) and 2.256(1) angstrom, respectively. The H atoms of the imidazole nitrogens are hydrogen bonded to the chloride anions of neighbouring molecules (N...Cl contacts are 3.213 and 3.323 angstrom).