Syntheses and crystal structures of two mononuclear Zn(II) complexes with the 2,5-bis(2-pyridyl)-1,3,4-thiadiazole ligand

Crystal structure and minimum energy calculations show that 2,5-bis(2-pyridyl)-1,3,4-thiadiazole exists in the solid state in one of two minimum energy forms. Uncomplexed, both nitrogen atoms of the pyridyl rings facing in the direction of the sulfur atom of the five-membered hetero ring in the planar molecule. Two different single crystal structures of zinc complexed to this ligand with a Zn/ligand ratio of 1/2 show a rotation of one of the pyridyl rings of each ligand molecule to allow complexation of the metal to the pyridyl nitrogen atom of this ring and the near diazole nitrogen atom. Axial coordination to water molecules completes the octahedral geometry at zinc. (C) 2004 Elsevier Ltd. All rights reserved.