Synthesis and X-ray structural studies of Cd(II) and Ni(II) complexes of 5-(4-methoxy phenyl), 5-(2-pyridyl) and 5-(2-methoxy phenyl)-1,3,4-oxadiazole-2-thione

Three new mixed ligand complexes [Cd(en)2(4-mpot)2] (1) [Ni(2-pytone)2(en)2] (2) and [Ni(2-mpot)2(en)2] (3) {4-mpot = 5-(4-methoxy-phenyl)-1,3,4-oxadiazole-2-thione, 2-pytone = 5-(2-pyridyl)-1,3,4-oxadiazole-2-thione, 2-mpot = 5-(2-methoxy-phenyl)-1,3,4-oxadiazole-2-thione} have been prepared containing en as co-ligand. Potassium N-(4-methoxy benzoyl)-hydrazinecarbodithioate cyclized to 5-(4-methoxy-phenyl)-1,3,4-oxadiazole-2-thiol on addition of tetrabutylammonium bromide which then reacted with Cd(OAc)2·2H2O and ethylenediamine to form complex 1, whereas potassium N-(2-methoxy benzoyl/pyridine-2-carbonyl)-hydrazinecarbodithioates (RCONHNHCSSK) underwent cyclization during complexation in the presence of en to give the complexes of the corresponding 5-aryl-1,3,4-oxadiazole-2-thiones. The complexes have been characterized by physicochemical techniques and single crystal X-ray structure determination. In the complexes the metal center has a six coordinate octahedral arrangement coordinated by 4N atoms of two en and two covalently bonded N atoms of the oxadiazole-2-thione anions. All the complexes contain extended hydrogen bonding providing supramolecular framework.

► N-acylhydrazinecarbodithioate cyclized to oxadiazole-2-thiol in soln of (C4H9)4NBr.
► [Cd(en)2(4-mpot)2], [Ni(2-pytone)2(en)2] and [Ni(2-mpot)2(en)2] have been prepared.
► The complexes contain extended hydrogen bonding providing supramolecular framework.
► Cd complex is stabilized by π⋯π interaction between phenyl and oxadiazole rings.