Dinuclear copper(II) chloro complex of the ligand 2,3,5,6-tetra(2-pyridyl)pyrazine

Crystallographic and magnetic studies have been performed on the complex, [{CuCl}2(μ-tppz)][PF6]2, where tppz is 2,3,5,6-tetra-2-pyridinylpyrazine. The crystal structure revealed an infinite, ionic chain wherein Cu(II) ions are respectively above and below the plane of the pyrazine moiety of the bridging tppz ligand with the pyridine moieties moving out of the pyrazine plane in order to coordinate to Cu(II). Each chloride ligand bonds equatorially to Cu(II) in a [{CuCl}2(μ-tppz)]2+ ion and axially to a neighboring [{CuCl}2(μ-tppz)]2+ ion so as to form a one-dimensional chain in the solid state. The temperature-dependent magnetic susceptibilitity could be satisfactorily fitted by using a modified Bleaney–Bowers expression (for H = −JSa · SbJ = −5.6 cm−1 and g = 2.16) where the exchange interaction is suggested to involve the orbitals of the tppz ligand.