STRUCTURE OF DICOPPER COMPLEXES OF N,N,N',N'-TETRAKIS[(2-BENZIMIDAZOLYL)METHYL]-2-HYDROXY-1,3-DIAMINOPROPANE WITH CHLORIDE COUNTERIONS

The structures of four dicopper complexes of binucleating ligand HL-H (N,N,N',N'-tetrakis[(2-benzimidazolyl)methyl]-2-hydroxy-1,3-diaminopropane) with chloride counterions were investigated by the X-ray diffraction method. In Cu-2(HL-H)Cl-4.2H(2)O.Et(2)O.CH3OH (a = 33.837(9) Angstrom, b = 9.648(3) Angstrom, c = 32.027(8) Angstrom, beta = 118.82(3)degrees, Z = 8, monoclinic, C2/2), 1, one chloride is not coordinated. A square pyramidal geometry is found for both the CuN3Cl2 and CuN3OCl coordination sites in which the N-3 tripodal coordination sites come from the two symmetric halves of the ligand. In Cu-2(HL-H)Cl-4.5H(2)O.2CH(3)OH.0.5CH(3)CN (a = 12.124(5) Angstrom, b = 14.354(5) Angstrom, c = 16.361(6) Angstrom, alpha = 67.52(3)degrees, beta = 89.97(3)degrees, gamma = 65.77(3)degrees, Z = 2, triclinic, P (1) over bar), 2, which was obtained from the same solution as that for 1 on addition of sodium azide, the basic coordination environments of the two copper ions are the same as in 1: CuN3Cl2 and CuN3OCl in square pyramidal geometry. 1 and 2 are rotational isomers. In Cu-2(HL-H)Cl-2(ClO4)(2).1.5Et(2)O.CH3OH (a = 11.684(4) Angstrom, b = 13.543(5) Angstrom, c = 17.750(7) Angstrom, alpha = 110.78(4)degrees, beta = 72.63(3)degrees, gamma = 109.67(3)degrees, Z = 2, triclinic, P (1) over bar), 3, the complex exists asa dimer; the two monomers are connected by two bridging chloride ions. The basic coordination environments of the two copper ions are square pyramidal CuN3Cl2 and CuN3OCl. In Cu-2(HL-H)Cl-2(ClO4)(2).5H(2)O.Et(2)O.C2H5OH (a = 11.70(2) Angstrom, b = 14.65(3) Angstrom, c = 19.45(4) Angstrom, alpha = 100.2(2)degrees, beta = 105.7(1)degrees, gamma = 107.0(2)degrees, Z = 2, triclinic, P (1) over bar), 4, the coordination of both copper ions is CuN3OCl; the hydroxy group bridges between two copper ions. However, the geometries of the two copper ions are distinct; one is square pyramidal, and the other is distorted trigonal bipyramidal. Together with the known structures of dicopper complexes of HL-Et, HL-H types of ligands are obviously flexible. The distances between the two copper ions in each monomer are in the range 4.9-7.2 Angstrom. All copper ions in 1-4 are pentacoordinate. This tendency of tripodal N-3 coordinated Cu(II) to form pentacoordinate Cu(II). is used to rationalize the structures of 1-4. The endogenous hydroxy groups in 1-4 do not deprotonate. 1-4 are the first reported structurally characterized examples of coordination of nondeprotonated alcoholic hydroxy groups to Cu(II) in dicopper complexes. In 4, the hydroxy group even bridges between two Cu(II) ions.