Crystal structure of cis-2,5-bis(3-pyridyl)-1,3,4-thiadiazole, C12H8N4S

Abstract

Source of material 2,5-Bis(3-pyridyl)-1,3,4-thiadiazole was prepared similarly to the literature procedure [1]. A mixture of nickel acetate monohydrate (0.026 g, 0.1 mmol), 2,5-bis(3-pyridyl)-1,3,4-thiadiazole (0.024 g, 0.1mmol), 2,2-dipy-4,4-bicarboxylic acid (0.012 g, 0.05 mmol), ethanol (5 ml) and 25 % ammonia water (3 ml) was sealed in a 15 ml Teflon-lined stainless steel reactor. The reactor was heated in an oven at 180°C for 72 hours and then cooled to room temperature at a rate of 10°C/h. Yellow needlelike crystals were obtained. DiscussionThe crystal structure of trans-2,5-bis(3-pyridyl)-1,3,4-thiadiazole has been already reported [2], and the structures of its other isomers (4-pyridyl or 2-pyridyl-1,3,4-thiadiazole) have been previously X-ray characterized [3][4][5]. The two pyridyl rings within each molecule (figure, top) form a dihedral angle of 20.78(5)°with the mean plane difined by the central thiadiazole ring, which is larger than those in the trans-2,5-bis(3-pyridyl)-1,3,4-thiadiazole molecule. There is a 2-fold axis through the middle point of the N-N bond in the thiadiazole ring and the sulfur atom. There are C−H···N hydrogen bonds between cis-2,5-bis(3-pyridyl)-1,3,4-thiadiazole molecules with the distance of H···A about 2.95 Å (figure, middle). Another kind of intermolecular interaction is C−H···p interactions (figure, bottom). The distance between hydrogen atom and the center of aromatic pyridyl ring is about 2.8 Å. Furthermore, it is interesting that cis-and trans -2,5-bis(3-pyridyl)-1,3,4-thiadiazole are synthesized under very different conditions. This indicates that factors like temperature, metal ions, other organic compounds in the reaction mixture may affect the conformation of the organic molecules.

Tuning of the Electrostatic Potentials on the Surface of the Sulfur Atom in Organic Molecules: Theoretical Design and Experimental Assessment

“…All these chemicals were used as received. The 3-BPTD has both cis and trans isomers [43,44]. As shown in Figure 1, we only considered the cis isomer of 3-BPTD in this work.…”