EPR and Magnetic Studies of a Carboxylate-Bridged Dinuclear Copper(II) Compound: [Cu-2(flu)(4)(dmf)(2)]

Author(s)

Nascimento, Otaciro R. ^[1] ; Napolitano, Lia M. B. ^[1] ; Torre, Maria H. ^[2] ; Pena, Octavio ^[3] ; Calvo, Rafael ^{[4, 5]}

Affiliation

^[1] Univ Sao Paulo, Grp Biofis Mol Sergio Mascarenhas, Dept Fis & Informat, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

^[2] Univ Republ UDELAR, Montevideo - Uruguay

^[3] Univ Rennes 1, CNRS, UMR Sci Chim Rennes 6226, F-35042 Rennes - France

^[4] Univ Nacl Litoral, Fac Bioquim & Ciencias Biol, RA-3000 Santa Fe - Argentina

^[5] INTEC CONICET UNL, RA-3000 Santa Fe - Argentina

• Document type: Journal article
• Source: Journal of the Brazilian Chemical Society; v. 22, n. 4, p. 669-676, 2011.
• Web of Science Citations: 3

Abstract

We report magnetic and EPR (electron paramagnetic resonance) spectroscopy studies of {[} Cu(2)(flu)(4)(dmf)(2)] (flu = flufenamate and dmf = dimethylformamide), which has Cu(II) ions in tetracarboxylate ``paddle wheel{''} dinuclear units. Susceptibility measurements at 10 = T = 275 K allowed the evaluation of an antiferromagnetic intradinuclear exchange coupling J(0) = -294 +/- 5 cm(-1) between Cu(II) ions (H(ex) = -J(0) S(1)center dot S(2)). EPR experiments at 300 K in powder and single-crystals at 9.5 and 34.4 GHz indicated g(parallel to) = 2.373, g(perpendicular to) = 2.073 and zero field splitting parameters D = (-0.334 +/- 0.001) cm(-1) and E ca. 0. EPR signal intensity measurements at X-band in the range 4 <= T <= 295 K indicated that J(0) = -283 +/- 5 cm(-1). A higher limit vertical bar J'vertical bar < 5x10(-3) cm(-1) for the interdinuclear exchange coupling between neighbor units at ca. 14.24 angstrom was estimated from the angular variation of the single crystal spectra around the magic angles. The results are discussed in terms of the structure of the dinuclear unit and the bridges connecting Cu(II) ions and compared with values reported for similar compounds. (AU)

• FAPESP's process: 03/09859-2 - Electron paramagnetic resonance in structural studies of proteins, peptides, biomembranes, polymers, model molecules and their complexes with transition metals
• Grantee: Otaciro Rangel Nascimento
• Support Opportunities: PRONEX Research - Thematic Grants