SYNTHESIS AND CHARACTERIZATION OF THE COMPLEXES [CU(II)(ET4TODIT)X2]N.NTHF (ET4TODIT=4,5,6,7-TETRATHIOCINO[1,2-B-3,4-B']-DIIMIDAZOLYL-1,3,8,10-TETRAETHYL-2,9-DITHIONE X = CL, BR) - CRYSTAL AND MOLECULAR-STRUCTURE OF [CU(II)(ET4TODIT)CL2]N.NTHF

By reacting CuX2 (X = Cl or Br) with Et4todit (Et4todit = the title ligand) in THF, the new ligand-bridged polynuclear complexes [Cu(II)(Et4todit)X2]n.nTHF have been obtained. The X-ray crystallographic studies on the Cl derivative show that the compound crystallizes in the orthorhombic space group Fdd2, with a = 32.674(6), b = 34.547(6), c = 10.162(3) angstrom, Z = 16. The coordination around the metal involves two Cl- ions and two S-thioamide atoms of two ligand molecules related by a screw axis, and is nearer to a square planar than to a tetrahedral arrangement. The bridging ligands form helical chains running parallel to c. The copper-copper distances in and between the chains are 7.601(4) and 9.185(5) angstrom, respectively. ESR measurements on this polymer give g values in accordance with a strongly distorted rhombic structure. The magnetic susceptibility data within the temperature range 5-150 K exhibit a Curie behaviour for both complexes (mu = 1.82 and 1.72 BM for Cl and Br complexes, respectively). Electronic spectroscopic results show that: (i) the environment around the copper(II) is the same in the solid state and in THF solution; (ii) reagents and products exist in THF at supersaturation conditions; (iii) S-(thioamide)copper(II) LMCT bands are observed at 555 and 620 nm for Cl and Br complexes, respectively. IR spectra agree with the X-ray structural results.