SYNTHESIS AND SPECTROSCOPY OF COPPER(II) COMPOUNDS OF A CHELATING IMIDAZOLE THIOETHER LIGAND - MOLECULAR-STRUCTURES OF (1,5-BIS(4-IMIDAZOLYL)-3-THIAPENTANE)DICHLOROCOPPER(II), (1,5-BIS(4-IMIDAZOLYL)-3-THIAPENTANE)BIS(THIOCYANATO-N)COPPER(II), AND BIS[(MU-CHLORO)(1,5-BIS(4-IMIDAZOLYL)-3-THIAPENTANE)COPPER(II)] BIS(PERCHLORATE)

The synthesis and characterization of copper coordination compounds with the novel tridentate ligand l,5-bis(4-imidazolyl)-3-thiapentane (abbreviated as bimtp) are described. The compounds are of the general formula [Cu(bimtp)X2] with X- = Cl-, Br-, NO3-, and NCS’. Also, compounds with mixed anions were isolated with general formula [Cu(bimtp)X]Y with X- = Cl- and Y- = ClO4- and BF4-. bimtp acts as a tridentate ligand in all compounds, both imidazole nitrogens and the thioether sulfur participating in the coordination of copper. All compounds of the formula [Cu(bimtp)X2] are five-coordinated in a distorted trigonal-bipyramidal or distorted square-pyramidal geometry. In the chloro-bridged dimer [Cu(bimtp)Cl]2(ClO4)2, the copper ion is five-coordinated in a square pyramid. Single crystals of [Cu(bimtp)Cl2], [Cu(bimtp)(NCS)2], and [Cu(bimtp)Cl]2(ClO4)2 were used for structure determinations, using heavy-atom techniques and refined by least-squares methods. [Cu(bimtp)Cl2]: orthorhombic, space group P212121, a = 7.605 (2) Å, b = 8.280 (1) Å, c = 22.644 (5) Å, Z = 4, T = 293 K; R = 0.032, Rw = 0.040 for 1605 reflections; Cu-N = 1.97 Å, Cu-Cl = 2.48 and 2.32 Å, Cu-S = 2.50 Å, in an almost ideal trigonal-bipyramidal geometry. [Cu(bimtp)(NCS)2]: monoclinic, space group P21/n, a = 13.000 (2) Å, b = 16.400 (3) Å, c = 8.131 (1)Å, β= 105.9 (1)°, Z = 4, T = 293 K; R = 0.045, Rw = 0.047 for 3035 reflections; Cu-N = 1.96 and 1.98 Å, Cu-NCS = 1.99 and 2.00 Å, Cu-S = 2.60 Å, in a distorted trigonal-bipyramidal geometry. [Cu(bimtp)Cl]2(CI04)2: monoclinic, space group P21/c, a = 8.703 (2) Å, b = 13.776 (3) Å, c = 12.857 (2) Å, β = 97.47 (2)°, Z = 2, T = 293 K; R = 0.046, Rw = 0.057 for 3151 reflections; Cu-N = 1.95 Å, Cu-Cl = 2.31 Å, Cu-Cl’ = 2.86 Å, Cu-S = 2.42 Å, Cu-Cu = 3.55 Å, in a distorted square-pyramidal geometry. The compounds were characterized further by EPR and ligand field spectroscopy. Cyclic voltammetry of [Cu(bimtp)Cl2] and [Cu(bimtp)CI]2(ClO4)2 yielded quasi-reversible waves with E°’ between 0.07 and 0.16 V (with respect to SCE). © 1990, American Chemical Society. All rights reserved.