title: Novel copper(II)-dien-imidazole/imidazolate-bridged copper(II) complexes. Crystal structure of [Cu(dien)(Him)](ClO4)2 and of [(dien)Cu(mu-im)Cu(dien)](ClO4)3, a homobinuclear model for the copper(II) site of the CuZn-superoxide dismutase.
abstract: The imidazolate-bridged binuclear copper(II)-copper(II) complex [(dien)Cu(mu-im)Cu(dien)](ClO(4))(3) and related mononuclear complexes [Cu(dien)(H(2)O)](ClO(4))(2), [Cu(dien)(Him)](ClO(4))(2) were synthesized with diethylenetriamine (dien) as capping ligand. The crystal structure of mononuclear [Cu(dien)(Him)](ClO(4))(2) and binuclear complex [(dien)Cu(mu-im)Cu(dien)](ClO(4))(3) have been determined by single crystal X-ray diffraction methods. The mononuclear complex [Cu(dien)(Him)](ClO(4))(2) crystallizes in the orthorhombic, Pca2(1) with a = 9.3420(9) A, b = 12.3750(9) A, c = 14.0830(9) A, beta = 90.000(7)(o) and Z = 4 and binuclear complex [(dien)Cu(mu-im)Cu(dien)](ClO(4))(3) crystallizes in the monoclinic space group P2(1)/a, with a = 15.017(7) A, b = 11.938(6) A, c = 15.386(6) A, beta = 110.30(4)(o) and Z = 4. The molecular structures show that copper(II) ions in an asymmetrically elongated octahedral coordination (type 4 + 1 + 1) and in binuclear complex Cu(1) atom has a asymmetrically elongated octahedral coordination (type type 4 + 1 + 1) and Cu(2) atom exhibits a square base pyramidal coordination (type 4 + 1). The bridging ligand (imidazolate ion, im) lies nearly on a straight line between two Cu(2+), which are separated by 5.812 A, slightly shorter than the value in copper-copper superoxide dismutase (Cu(2)-Cu(2)SOD). Magnetic measurements and electron spin resonance (ESR) spectroscopy of the binuclear complex have shown an antiferromagnetic exchange interaction. From pH-dependent cyclic voltametry (CV) and electronic spectroscopic studies the complex has been found to be stable over a wide pH range (7.75-12.50).
authors.affiliation: Department of Chemistry A.P.S. University, Rewa, MP 486003, India. rnp64@yahoo.co.uk
authors.forename: R N
authors.initials: RN
authors.lastname: Patel
authors.forename: Nripendra
authors.initials: N
authors.lastname: Singh
authors.forename: K K
authors.initials: KK
authors.lastname: Shukla
authors.forename: U K
authors.initials: UK
authors.lastname: Chauhan
mesh_terms: D000042:Absorption; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002244:Carbon / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D004566:Electrodes; D004578:Electron Spin Resonance Spectroscopy; D005898:Glass; D006863:Hydrogen-Ion Concentration; D008280:Magnetics; D008956:Models, Chemical; D008968:Molecular Conformation; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D012996:Solutions; D013482:Superoxide Dismutase / Q000737:chemistry* / Q000378:metabolism
chemical_list: C500449:((diethylenetriamine)copper(II)(mu-imidazolate)copper(II)(diethylenetriamine)) perchlorate; C500448:(diethylenetriamine)(imidazoline)copper(II) perchlorate; D000900:Anti-Bacterial Agents; D009942:Organometallic Compounds; D012996:Solutions; D002244:Carbon; D003300:Copper; D013482:Superoxide Dismutase