THE PREPARATION OF SOME THIOSEMICARBAZONES AND THEIR COPPER COMPLEXES: PART III

Abstract

Reactions of some diketones with thiosemicarbazide have been studied under various conditions. Monothiosemicarbazones, dithiosemicarbazones, and cyclization products can be obtained. It was found that dithiosemicarbazones form 1:1 complexes with Cu(II) but failed to react with Cu(I). Dithiosemicarbazones in which the N²-hydrogen atom has been replaced by Me do not form complexes, confirming our views about the importance of this hydrogen atom in the thione ↔ thiol tautomerism necessary for complex formation. 4,4-Dimethyldithiosemicarbazones behave like the unsubstituted parent compounds in forming 1:1 complexes with Cu(II). Infrared spectra provide evidence for the structure of a cyclization product, 5,6-diphenyl-3-thio-1,2,4-triazine, which had been erroneously described by various authors as the thiol tautomer, 5,6-diphenyl-3-mercapto-1,2,4-triazine.