Reaction of diacetylmonoxime with morpholine N-thiohydrazide in the absence and in presence of a metal ion: Facile synthesis of a thiadiazole derivative with non-bonded S...S interaction

The condensation of diacetylmonoxime (damnx) with morpholine N-thiohydrazide (mth) in 1:1 molar ratio in ethanol (16 h) afforded a nitrogen-sulfur zwitterionic heterocyclic compound, N-(3,4-dimethyl-1,2,5-thiadiazole-2-ium-2-yl)morpholine-4-carbothioate (dtmc). However, the same reaction in presence of [Zn(OAc)(2)]center dot 2H(2)O in ethanol under gentle reflux on (3 h) yielded the zinc complex, [Zn(Hdammthiol)(OAc)(H(2)O)]center dot H(2)O, where H(2)dammthiol (H(2)L(2)) is the thiol form of tridentate NNS donor thiohydrazone ligand, diacetylmonoxime morpholine N-thiohydrazone (Hdammth). Both the nitrogen-sulfur heterocyclic compound and the zinc complex have been characterized by elemental analyses, spectroscopy (IR, UV-Vis, (1)H NMR and (13)C NMR) and single crystal X-ray crystallography. It is noteworthy that the heterocyclic compound shows S center dot center dot center dot S interaction with distance 2.738 angstrom in its planar conformation. The heterocyclic compound forms two dimensional supramolecular sheets through C-H center dot center dot center dot O and pi center dot center dot center dot pi interactions while the zinc complex, with distorted square pyramidal geometry, forms I D supramolecular chain. A mechanism has been proposed for the formation of nitrogen-sulfur heterocyclic compound. (C) 2009 Elsevier Ltd. All rights reserved.