Sulfadiazine/dimethylsulfadiazine transition metal complexes: Synthesis, crystal structures and magnetic properties

Abstract

Sulfadiazine (Hsulf) and dimethylsulfadiazine (Hdmsulf) were used to assemble divalent transition metal complexes (Cu, Ni or Co). Solvated complexes 1–4, dinuclear 1 (Cu2), tetranuclear 2 (Ni4) and 3 (Co4), and two-dimensional polymeric 4, were synthesized by controlling the metal ions, ligands and solvents. For complex 1, two Cu(II) ions are bridged by four NCN groups of four sulf− ligands, while for complex 2, four Ni(II) ions are alternatively bridged by the pyrimidine rings of four sulfadiazine ligands, forming a neutral square Ni4 molecule. In complex 3, four Co(II) ions are bridged by four μ3-OMe− groups, yielding a Co4O4 cubane. Complex 4 possesses a 2D grid structure with the Co(II) ions bridged by the remote amino groups of the ligand dmsulf−. Magnetic susceptibility measurements show that the desolvated complex (1d) exhibits antiferromagnetic coupling between adjacent Cu(II) ions with the 2J value of −90.0cm−1, and the pyrimidine rings transmit weak antiferromagnetic coupling in complex 2. Complex 3·8H2O shows ferromagnetic coupling via the methoxido bridges with the bridging CoOCo bond angles of 96–99°. Complex 4 displays a magnetic property for mononuclear cobalt(II) complexes due to the remote separation of Co(II) ions.