Synthesis of 5-acetyl-4,6-dimethyl-1,2,3,4-tetrahydropyrimidine-2-thione and structural characterization of its polymorphs and complexes with 12-group metal iodides

Abstract

A novel cyclic thiourea, 5-acetyl-4,6-dimethyl-1,2,3,4-tetrahydropyrimidine-2-thione (L), was synthesized by the reaction of N-(1-tosylethyl)thiourea with potassium enolate of acetylacetone followed by acid-catalyzed dehydration of the obtained 5-acetyl-4-hydroxy-4,6-dimethylhexahydropyrimidine-2-thione. Its polymorphs and complexes with zinc, cadmium, and mercury iodides were studied by X-ray diffraction. Two polymorphs of 5-acetyl-4,6-dimethyl-1,2,3,4-tetrahydropyrimidine-2-thione differ in ring conformation and packing manner. In the monomeric cadmium complex [CdL2I2], the central atom is tetrahedrally coordinated in the standard manner by iodine and thiocarbonyl S atoms, while in the dimeric mercury complex [Hg2L2I4], every mercury atom is coordinated by two bridging I atoms, one terminal I atom and one thiocarbonyl S atom of the ligand. In the polymeric zinc complex [ZnLI2], the zinc tetrahedra are linked by the bidentate bridging 5-acetyl-4,6-dimethyl-1,2,3,4-tetrahydropyrimidine-2-thione molecules through thiocarbonyl S atom and acetyl O atom.