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

Sulfadiazine (Hsulf) and dimethylsulfadiazine (Hdmsulf) were used to assemble divalent transition metal complexes (Cu, Ni or Co). Solvated complexes 1-4, dinuclear 1 (Cu-2), tetranuclear 2 (Ni-4) and 3 (Co-4), 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 N=C-N 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 Ni-4 molecule. In complex 3, four Co(II) ions are bridged by four mu(3)-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 -90.0 cm(-1), and the pyrimidine rings transmit weak antiferromagnetic coupling in complex 2. Complex 3.8H(2)O shows ferromagnetic coupling via the methoxido bridges with the bridging Co-O-Co bond angles of 96-99 degrees. Complex 4 displays a magnetic property for mononuclear cobalt(II) complexes due to the remote separation of Co(II) ions. (C) 2015 Elsevier Ltd. All rights reserved.