Structure and magnetic properties of one-dimensional metal complexes constructed from alternating dicyanamide linked through binuclear metal tetra-2-pyridylpyrazine subunits

Abstract

The syntheses, structures and magnetic properties of three 1-D complexes with the formulae [Co 2(tppz)(dca) 4] ( 1), [Ni 2(tppz)(dca) 4]C 2H 5OH ( 2) and [Cu 2(tppz)(dca)(Cl) 2](dca) · H 2O ( 3), where tppz = tetra-2-pyridylpyrazine and dca = dicyanamide, are described. Complexes 1– 3 are one-dimensional metal-complexes. In 1 the dinuclear tppz-chelated Co(II) centers are linked by two double μ 1,5-dca ligands. Compound 2 forms a ladder-like structure in which the rungs are formed by bis-chelating tppz bridged dinuclear Ni(II) ions and the uprights by μ 1,5-dca units. Compound 3 forms a helical chain structure which consists of alternately single μ 1,5-dca linked dinuclear tppz-chelated Cu-centers. The temperature dependence of magnetic measurements show antiferromagnetic couplings between two metal ions with a pathway through tppz and μ 1,5-dca in all cases, with J = −1.10 cm −1, J′ = −0.05 cm −1 for 1, J = −1.28 cm −1, J′ = −0.11 cm −1 and D = 9.50 cm −1 for 2, and J = −10.26 cm −1, J′ = −0.06 cm −1 for 3.