E.S.R., magnetic, electronic and superoxide dismutase studies of imidazolate-bridged Cu(II)–Cu(II) complexes with ethylenediamine as capping ligand

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2005-06, Vol.61 (8), p.1893-1897
• Main Authors: Patel, R.N., Singh, Nripendra, Shukla, K.K., Gundla, V.L.N.
• Format: Article
• Language: English
• Subjects: Binding Sites; Copper - chemistry; E.S.R. spectroscopy; Electromagnetic Fields; Electron Spin Resonance Spectroscopy - methods; Electronic spectroscopy; Electrons; Ethylenediamines - chemistry; Hydrogen-Ion Concentration; Imidazolate-bridged copper(II) complexes; Imidazoles - chemistry; Inhibitory Concentration 50; Ligands; Magnetics; Models, Chemical; Molecular Conformation; Organometallic Compounds - chemistry; Spectrophotometry; Superoxide Dismutase - chemistry; Superoxide models; Superoxides - chemistry; Temperature
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2004.07.019

X-band E.S.R., magnetic and electronic spectra of some imidazolate-bridged homometallic complexes [(en) 2Cu- R-Im-Cu(en) 2](ClO 4) 3 where en, ethylenediamine; R-ImH, R = H imidazole (ImH); if R = CH 3, 2-methylimidazole (M-ImH) and if R = C 2H 5, 2-ethylimidazole (E-ImH), and mononuclear complexes [(en)Cu-dien](ClO 4) 2 and [(en)Cu-PMDT](ClO 4) 2 where dien, diethylenetriamine; PMDT, pentamethyldiethylenetriamine have been described. Superoxide dismutase (SOD) activity has also been measured and compared with earlier reported complexes. In frozen solution at 77 K, the spectra show axial symmetry with a d x 2 - y 2 ground state. Difference in λ max between mononuclear and binuclear complexes was found to be ∼65–75 nm. Magnetic susceptibility and E.S.R. spectral measurements for all these binuclear complexes revealed that the copper(II) ions are involved in antiferromagnetic exchange interactions propagated by the imidazolate bridge.