COPPER COORDINATION-COMPOUNDS OF POLYIMIDAZOLE THIOETHER LIGANDS - X-RAY STRUCTURES AND CHARACTERIZATION OF (BIS[4-((METHYLTHIO)ETHYL)IMIDAZOL-2-YL]METHANE)BIS(TETRAFLUOROBORATO)COPPER(II), DICHLORO((IMIDAZOL-2-YL)[4-((METHYLTHIO)ETHYL)IMIDAZOL-2-YL]METHANE)COPPER(II), AND ([4-(IMIDAZOL-2-YLMETHYL)IMIDAZOL-2-YL][4-((METHYLTHIO)ETHYL)IMIDAZOL-2-YL]METHANE)-BIS(PERCHLORATO)COPPER(II)

The synthesis and characterization of copper coordination compounds with the polyimidazole-thioether ligands bis[4-((methylthio)ethyl)imidazol-2-yl]methane (L1), [4-((methylthio)ethyl)imidazol-2-yl] (imidazol-2-yl]methane (L2), and [4-((methylthio)ethyl)imidazol-2-yl] [4-(imidazol-2-ylmethyl)imidazol-2-yl]methane (L3) are described. The study of these new complexes is aimed at modeling the active site of blue-copper proteins. Single crystals of these complexes were used for structural determinations. [Cu(L1)(BF4)2]: monoclinic, space group P2(1)/n, a = 12.252(4) angstrom, b = 19.782(3) angstrom, c = 8.954(3) angstrom, beta = 108.72(1)degrees, Z = 4, T = 291 K, R = 0.056, R' = 0.062 for 1261 reflections; Cu-N = 2.01(1) and 1.99(1) angstrom; Cu-S = 2.363(4) and 2.361(4) angstrom; fluorine atoms occupy the axial positions at the distances of 2.65(1) and 2.565(8) angstrom to Cu, in a distorted octahedral geometry. [Cu(L2)Cl2]: monoclinic, space group P2(1)/a, a = 13.48(1) angstrom, b = 11.721(9) angstrom, c = 9,997(7) angstrom, beta = 108.86(5)degrees, Z = 4, T = 291 K, R = 0.060, R'= 0.068 for 870 reflections; Cu-N = 2.01(1) and 2.00(1) angstrom, Cu-S = 2.387(5) angstrom, Cu-Cl = 2.279(4) and 2.660(4) angstrom, in a distorted square pyramidal geometry. [Cu(L3)(ClO4)2]: triclinic, space group P1BAR, a = 8.679(6) angstrom, b = 9.866(2) angstrom, c = 12.445(1) angstrom, alpha = 82.46(2)degrees, beta = 85.80(5)degrees, gamma = 88.21(2)degrees, Z = 2, T = 291 K, R = 0.082, R' = 0.089 for 511 reflections; Cu-S = 2.40(2) angstrom, Cu-N = 1.90(4), 1.94(4), and 1.98(3) angstrom; oxygen atoms occupy the axial positions at the distances of 2.90(4) and 2.96(5) angstrom to Cu, in a distorted octahedral geometry. Cyclic voltammograms of Cu(L1)2+ and Cu(L2)2+ complexes exhibit two waves due to the presence of the monoligand and bis-ligand complexes in Solution. The Cu(L3)2+ complex shows only one quasi-reversible wave. The compounds were further characterized by electronic, EPR, and ESEEM spectroscopies.