Structure of Dicopper Complexes of N,N,N‘,N‘-Tetrakis[(2-benzimidazolyl)methyl]-2-hydroxy-1,3-diaminopropane with Coordinated Thiocyanate Counterions

• Published in: Inorganic chemistry 1996-04, Vol.35 (8), p.2259-2267
• Main Authors: Zeng, Weng Feng, Cheng, Cheu Pyeng, Wang, Sung Mao, Lee, Gene-Hsian
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic951432r

The structures of five dicopper complexes of binucleating ligand HL-H (N,N,N‘,N‘-tetrakis[(2-benzimidazolyl)methyl]-2-hydroxy-1,3-diaminopropane) with thiocyanate and some other counterions were investigated by the X-ray diffraction method. In Cu2(HL-H)(NCS)2Cl2·6H2O·CH3OH, 1 (a = 12.524(5) Å, b = 14.429(4) Å, c = 16.343(3) Å, α = 109.01(2)°, β = 92.62(2)°, γ = 115.27(3)°, Z = 2, triclinic, P1̄), one chloride is not coordinated. Distorted square pyramidal (SP) geometry is found for both CuN3ClN and CuN3ON coordination sites in which the N3 tripodal coordination sites come from the two symmetric halves of HL-H and the other nitrogen atoms come from thiocyanate ions. In Cu2(HL-H)(NCS)2(ClO4)2·6H2O·2EtOH, 2 (a = 10.955(2) Å, b = 15.366(5) Å, c = 18.465(9) Å, α = 65.57(4)°, β = 89.73(3)°, γ = 79.81(2)°, Z = 2, triclinic, P1̄), the coordination environments for the two copper ions are both CuN3ON. However, their geometries are different:  one is distorted SP and the other is distorted trigonal bipyramid (TBP). In Cu2(HL-H)(NCS)2(ClO4)2Cl·H3O·3.5H2O, 3 (a = 11.986(6) Å, b = 12.778(5) Å, c = 17.81(1) Å, α = 82.41(4)°, β = 75.44(5)°, γ = 78.46(4)°, Z = 2, triclinic, P1̄), the chloride ion does not coordinate to copper ion, but it is hydrogen bonded to the hydroxy hydrogen. The coordination environments for the two copper ions are both CuN3ON with distorted SP geometries. In Cu2(HL-H)(NCS)Cl3·6H2O, 4 (a = 12.026(5) Å, b = 14.369(6) Å, c = 16.430(6) Å, α = 111.64(3)°, β = 90.51(4)°, γ = 113.90(3)°, Z = 2, triclinic, P1̄), one chloride does not coordinate. The coordination environments for the two copper ions are CuN3ON in severely distorted TBP geometry and CuN3Cl2 in SP geometry. In Cu2(HL-H)(NCS)3OH·2H2O·3CH3OH·Et2O, 5 (a = 18.322(5) Å, b = 15.543(6) Å, c = 19.428(7) Å, β = 102.78(3)°, Z = 4, monoclinic, P21/c), the hydroxide ion does not coordinate. The coordination environments for the two copper ions are CuN3N2 with a geometry inbetween SP and TBP but slightly closer to SP and CuN3ON in distorted SP geometry. The distances between the copper ions are in the range 4.45−7.99 Å, indicating negligible interaction between the copper ions. The hydroxy groups of HL-H in 1−5 all coordinate to copper ions either in a terminal mode (in complexes 1, 4, and 5, denoted as OHR(t)) or in a bridging mode (in complexes 2 and 3, denoted as OHR(b)). These hydroxy groups do not lose their protons in all cases. All thiocyanate anions coordinate to copper ions through nitrogen atoms