PREPARATION AND CHARACTERIZATION OF POLYMERIC COMPOUNDS OF COPPER(I) HALOGENIDES WITH ET4TODIT = 4,5,6,7-TETRATHIOCINO[1,2-B-3,4-B']DIIMIDAZOLYL-1,3,8,10-TETRAETHYL-2,9-DITHIONE - CRYSTAL AND MOLECULAR-STRUCTURES OF [CU(I)(ET4TODIT)I]N AND [CU(I)(ET4TODIT)I]N.N/2ME2CO

The complexes [Cu(II)(Et4todit)X2] (Et4todit = title ligand, X = Cl or Br) are reduced at very positive reduction potential. Cyclic voltammograms on their CH2Cl2 solutions exhibit a quasi-reversible process with E1/2 = 0.68 (Cl) and 0.48 (Br) V versus SCE. The reduced species have been chemically prepared by reacting CuX2 (X = Cl and Br) with Et4todit in the presence of an appropriate reducing agent. When the reducing agent is hydroquinone in organic solvents, yellow products analyzed as Cu2(Et4todit)X2 are obtained by concentration. When the reducing agent is I- in Me2CO, the obtained product gives instead an elemental analysis according to Cu(Et4todit)I (compound 1), which can also crystallize with 1/2Me2CO (compound 2). X-ray results on crystals of compounds 1 and 2 have shown that the compounds crystallize in the orthorhombic crystal system; space group P2(1)2(1)2(1), Z = 4, with a = 19.792(5), b = 14.167(4), c = 8.537(4) angstrom (compound 1) and a = 22.088(7), b = 14.414(6), c = 8.807(6) angstrom (compound 2). The coordination around Cu(I) is trigonal in both compounds and involves the iodide ion and two S atoms of two ligand molecules related by a screw axis. Both metal and ligand are bridging and polymeric chains parallel to b are formed. The solvent in 2 produces a different disposition of the adjacent chains and as a consequence interactions of the type S...S between the chains are observed only in this compound. IR spectroscopic results agree with a thionic-sulfur coordination. Moreover in the low-frequency region, bands attributed to the metal-halogen vibrations are observed and their positions suggest that Cl and Br are bridging while the I atom is terminal as shown by X-ray results.