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Structure and magnetism in Fe-Gd based dinuclear and chain systems. The interplay of weak exchange coupling and zero field splitting effects.
Ferbinteanu, Marilena; Cimpoesu, Fanica; Gîrtu, Mihai A; Enachescu, Cristian; Tanase, Stefania.
Afiliación
  • Ferbinteanu M; University of Bucharest , Faculty of Chemistry, Inorganic Chemistry Department, Dumbrava Rosie 23, Bucharest 020462, Romania. marilena.cimpoesu@g.unibuc.ro
Inorg Chem ; 51(1): 40-50, 2012 Jan 02.
Article en En | MEDLINE | ID: mdl-22148713
The synthesis and characterization of two Fe-Gd systems based on bpca(-) (Hbpca = bis(2-pyridilcarbonyl)amine) as bridging ligand is presented, taking the systems as a case study for structure-property correlations. Compound 1, [Fe(LS)(II)(µ-bpca)(2)Gd(NO(3))(2)(H(2)O)]NO(3)·2CH(3)NO(2), is a zigzag polymer, incorporating the diamagnetic low spin Fe(LS)(II) ion. The magnetism of 1 is entirely determined by the weak zero field splitting (ZFS) effect on the Gd(III) ion. Compound 2 is a Fe(III)-Gd(III) dinuclear compound, [Fe(LS)(III)(bpca)(µ-bpca)Gd(NO(3))(4)]·4CH(3)NO(2)·CH(3)OH, its magnetism being interpreted as due to the antiferromagnetic coupling between the S(Fe) = ½ and S(Gd) = 7/2 spins, interplayed with the local ZFS on the lanthanide center. In both systems, the d-f assembly is determined by the bridging capabilities of the ambidentate bpca(-) ligand, which binds the d ion by a tridentate moiety with nitrogen donors and the f center by the diketonate side. We propose a spin delocalization and polarization mechanism that rationalizes the factors leading to the antiferromagnetic d-f coupling. Although conceived for compound 2, the scheme can be proposed as a general mechanism. The rationalization of the weak ZFS effects on Gd(III) by multiconfiguration and spin-orbit ab initio calculations allowed us to determine the details of the small but still significant anisotropy of Gd(III) ion in the coordination sites of compounds 1 and 2. The outlined methodologies and generalized conclusions shed new light on the field of gadolinium coordination magnetochemistry.

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: Inorg Chem Año: 2012 Tipo del documento: Article País de afiliación: Rumanía Pais de publicación: Estados Unidos

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: Inorg Chem Año: 2012 Tipo del documento: Article País de afiliación: Rumanía Pais de publicación: Estados Unidos