title: Ferromagnetic interaction in an asymmetric end-to-end azido double-bridged copper(II) dinuclear complex: a combined structure, magnetic, polarized neutron diffraction and theoretical study.
abstract: A new end-to-end azido double-bridged copper(II) complex [Cu(2)L(2)(N(3))2] (1) was synthesized and characterized (L=1,1,1-trifluoro-7-(dimethylamino)-4-methyl-5-aza-3-hepten-2-onato). Despite the rather long Cu-Cu distance (5.105(1) A), the magnetic interaction is ferromagnetic with J= +16 cm(-1) (H=-JS(1)S(2)), a value that has been confirmed by DFT and high-level correlated ab initio calculations. The spin distribution was studied by using the results from polarized neutron diffraction. This is the first such study on an end-to-end system. The experimental spin density was found to be localized mainly on the copper(II) ions, with a small degree of delocalization on the ligand (L) and terminal azido nitrogens. There was zero delocalization on the central nitrogen, in agreement with DFT calculations. Such a picture corresponds to an important contribution of the d(x2-y2) orbital and a small population of the d(z2) orbital, in agreement with our calculations. Based on a correlated wavefunction analysis, the ferromagnetic behavior results from a dominant double spin polarization contribution and vanishingly small ionic forms.
authors.affiliation: Université Claude Bernard Lyon-1, Laboratoire des Multimatériaux et Interfaces (UMR 5615), Campus de La Doua, 69622 Villeurbanne Cedex, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Aronica
authors.forename: Erwann
authors.initials: E
authors.lastname: Jeanneau
authors.forename: Hani
authors.initials: H
authors.lastname: El Moll
authors.forename: Dominique
authors.initials: D
authors.lastname: Luneau
authors.forename: Béatrice
authors.initials: B
authors.lastname: Gillon
authors.forename: Antoine
authors.initials: A
authors.lastname: Goujon
authors.forename: Alain
authors.initials: A
authors.lastname: Cousson
authors.forename: Maria Angels
authors.initials: MA
authors.lastname: Carvajal
authors.forename: Vincent
authors.initials: V
authors.lastname: Robert