Single crystal E.P.R. spectra of copper(II) and manganese(II) doped ammonium tetrafluorozincate(II) dihydrate

Abstract

A detailed single crystal E.P.R. study of copper(II) in a low symmetry environment provided by the hexacoordinate complex (NH₄)2ZnF₄. 2H₂O is reported. Only two fluorines show hyperfine interaction. The analysis shows that the symmetry of the complex is D 2h similar to the corresponding ferromagnetic chloro and bromo complexes, viz. M ₂CuX ₄ . 2H₂O where M=NH₄ ⁺, K⁺, Rb⁺, Cs⁺ and X=Cl, Br. The effect of a low symmetry environment was further tested by doping Mn²⁺ in the same host lattice. There is a large D tensor with a small E showing departure from axial symmetry. There is excellent agreement between the experimental and theoretical line positions computed using third order perturbation theory. The determination of the orientation of the magnetic tensor components with respect to the molecular axes and metal and ligand hyperfine coupling parameters obtained by extensive computer simulation reveals the bonding properties of these complexes.