Unique Bridging Function of the Triazole Core in Copper(II) Chloride Complexes with 1-Allylbenzotriazole

During alternating-current electrochemical synthesis of copper(I) π-complex of [CuCl{C6H4N3(C3H5)}] composition, starting from ethanol solution, containing CuCl2·2H2O and 1-allylbenzotriazole, green crystals of intermediate [CuII3Cl6{C6H4N3(C3H5)}4] (I) compound has been obtained upon 24 h. After some days these crystals transform into red ones of [CuII2Cl4{C6H4N3(C3H5)}3] (II). Both compounds were X-Ray structurally investigated. Crystals of I are triclinic, sp.gr. a = 9.1329(9), b = 10.0352(4), c = 12.239(3) A, α = 76.443(13), β = 84.470(14), γ = 76.808(7)°, V = 1060.5(3) A3, R = 0.0414 for 3311 reflections. II: monoclinic, C2/c, a = 13.828(1), b = 15.044(2), c = 10.702(1) A, β = 91.36(1)°, V = 2225.7(4) A3, R = 0.050 for 1495 reflections. In both compounds each benzotriazole core coordinates two copper atoms using two nitrogen atoms in 2 and 3 positions. Isolated Cu3Cl6 fragments in I are condensed along [001] direction into infinite chains [CuCl2]n in II. Finally, red crystals of II transform into colorless ones of the earlier studied copper(I) π-complex of CuCl·C6H4N3(C3H5) composition.