Search

The behavior of [(eta(5):eta(1)-C(5)H(4)CH(2)CH(2)OMe)ZrCl(2)(&mgr;-Cl)](2) (1) toward a variety of solvents, and especially water, was investigated. The bidentate coordination of the C(5)H(4)CH(2)CH(2)OMe ligand is retained in chloroform, dichloromethane, benzene, acetone, thf, and acetonitrile. No stable adducts of 1 with the last three solvents could be isolated. In methanol and water, coordination of the ether side chain is broken; however, removal of solvent retains this coordination and the stable mono adducts (eta(5):eta(1)-C(5)H(4)CH(2)CH(2)OMe)ZrCl(3)(MeOH) and (eta(5):eta(1)-C(5)H(4)CH(2)CH(2)OMe)ZrCl(3)(H(2)O) were isolated. An X-ray structure of the thf solvate of the latter compound was determined: space group P2(1)/c, a = 11.612(1) Å, b = 10.759(2) Å, c = 14.291(2) Å, beta = 105.50(1) degrees, V = 1720.5(4) Å(3), Z = 4, R = 0.062. The intramolecular coordination of the ether side chain is also broken in DMSO, but in this case it is not retained after removal of solvent. A cationic aqua complex [(eta(5)-C(5)H(4)CH(2)CH(2)OMe)ZrCl(2)(H(2)O)(DMSO)(2)](+)Cl(-) crystallized from the solution: space group P&onemacr;, a = 8.297(1) Å, b = 10.097(1) Å, c = 12.883(1) Å, alpha = 71.12(1) degrees, beta = 86.60(1) degrees, gamma = 87.45(1) degrees, V = 1019.0(2) Å(3), Z = 2, R = 0.049. Compound 1 is a Diels-Alder catalyst even under moist conditions.

Two novel tridentate dinucleating ligands containing benzimidazole were prepared, 1,3-bis(2-benzimidazolyl)-2-propanol (Hbbp, 1) and 1,5-bis(2-benzimidazolyl)-3-pentanol (Hbbpen, 2). Their complexing properties toward copper were studied in order to obtain structural and functional models for catechol oxidases. Syntheses and crystal structures of dinuclear Cu(II) complexes derived from these ligands are reported. [Cu(2)bbp(2)](ClO(4))(2).2MeOH, 3, crystallizes in the triclinic space group P&onemacr; with the following unit cell parameters: a = 7.702(3) Å, b = 10.973(6) Å, c = 12.396(6) Å, alpha = 100.59(4) degrees, beta = 99.02(4) degrees, gamma = 98.90(4) degrees, V = 998.7(8) Å(3), and Z = 1. [Cu(2)bbpen(2)](ClO(4))(2).3MeOH, 4, crystallizes in the orthorhombic space group Pccn, with the following unit cell parameters: a = 17.478(9) Å, b = 18.795(8) Å, c = 13.888(6) Å, V = 4562.2(4) Å(3), and Z = 4. Magnetic susceptibility measurements in the temperature ranges 4.6-459 K (3) and 4.6-425 K (4) indicate an antiferromagnetic coupling between the Cu(II) centers of both complexes. In order to determine the structures of the complexes in solution, XAS spectra (EXAFS and XANES) were recorded in the solid state and in solution. The interpretation of these data, including multiple scattering calculations, together with UV-vis titrations, shows that the complexes have the same structure in the crystalline state as well as in methanolic solution. Complex 4 is able to oxidize 3,5-di-tert-butylcatechol (3,5-DTBC) to the quinone (catecholase activity). This reaction was also studied by XAS and UV-vis spectroscopy. These measurements reveal the reduction of Cu(II) to Cu(I) accompanied by a decrease of the coordination number.