Complexes of cobalt(II), nickel(II) and copper(II) with a thia ligand;: 2,5-bis(2-pyridyl)-1,3,4-thiadiazole:: structural identification

A heterocycle, previously untested as a polydentate ligand, 2,5-bis(2-pyridyl)-1,3,4-thiadiazole, namely bptd, has been found to form the monomeric complexes, Co(bptd)(2)(H2O)(2)(NO3)(2) (I), Ni(bptd)(2)(H2O)(2)(ClO4)(2) (II), Co(bptd)(2)(H2O)(2)(ClO4)(2) (III), and Cu(bptd)(2)(NO3)(2) (IV) with Co(II), Ni(II) and Cu(II) in the presence of nitrate or perchlorate anions. Despite similar syntheses, nitrate serves as a ligand to Cu(II) in IV whereas, it is seen as a free ion in the cell of Co(bptd)(2)(H2O)(2)(NO3)(2) (I). [GRAPHICS] (I) M=Co, A=H2O, C=NO3- (II) M=Ni, A=H2O, C= ClO4 (III) M=Co, A= H2O, C= ClO4- (IV) M=Cu, A= NO3- (C) 2002 Elsevier Science Ltd. All rights reserved.