Jean Jacques Girerd

Orbital interactions in a strongly antiferromagnetically coupled copper(II) linear chain: CuSe2O5

Abstract The structure of CuSe 2 O 5 is characterized by chains with Cu(II) ions aligned along the c -axis of the monoclinic lattice and bridged by Se 2 O 2− 5 ligands. The intrachain Cu-Cu separation is 3.98 A. The magnetic susceptibility of this compound, investigated in the 3.8–300 K temperature range, reveals a strong intrachain antiferromagnetic coupling. The J exchange parameter of the isotropic Heisenberg Hamiltonian — J Σ N i =1 S i S i + 1 ( N →∞) is found equal to − 95.1 cm −1 . From a previously described orbital model, an interpretation of this behavior is proposed: the interaction of the magnetic orbitals along the chain leads to a MO band, the width of which is related to the magnitude of the antiferromagnetic coupling. The top of the band corresponds to an antibonding interaction of the CuO 4 chromophores through the selenium lone pairs whereas the bottom of the band corresponds to a non-bonding interaction of these chromophores.