Pyridyldicarboxamide-based multinuclear complexes: Syntheses, structural characterizations, and magnetic properties

摘要

Using the pyridine dicarboxamide derivative N,N′-bis(1,3,4- thiadiazol-2-yl)-2,6-pyridinedi-carboxamide (H2-btapca) as ligand, two novel polynuclear complexes: dimeric {[Cu_2(μ_2- O_2H)(btapca)_2]·DMF·H_2O} (1) and tetrameric {[Ni_4((μ_2-O_2H) _2(btapca)_4)]·DMF·MeOH·3.5H _2O} (2) were obtained. In complex 1, two center Cu(II) ions are bounded by two btapca ligands and one aqueous molecule acting as a μ_2-H_2O bridge connect them together. Complex 2 is a tetrameric complex, in which the based backbone is an assumed Ni4 tetrahedron with two μ_2-O_2H bridges existing inside the tetrahedron forming a basic [Ni_2(μ_2-O _2H)]_2 core, which are surrounded by four btapca ligands. The magnetic properties of the two polynuclear complexes were determined, the results show that for both of the two complexes, the overall weak ferromagnetic exchange interactions between central metal ions are evident, the best fitting parameters are: J = 7.47 cm~(-1) (g = 2.21) for dimeric Cu(II) complex 1, and 2J_1 = 4.8 cm~(-1), 2J_2 = -0.00204 cm ~(-1)(g = 2.14, zJ′ = 0.00077 cm~(-1)) for tetrameric Ni(II) complex 2.