Crystal structure, spectroscopic and thermal properties of the coordination compounds M(1,3-diethyl-2-thiobarbiturate) M = Rb+, Cs+, Tl+ and NH4+

Four new compounds of 1,3-diethyl-2-thiobarbituric acid (C8H11N2O2S, Hdetba) with Rb+, Cs+, Tl+ and NH4+ ions were prepared by Hdetba neutralization with the metal carbonates or ammonium hydroxide in aqueous solution. The colorless crystals have been investigated using X-ray diffraction techniques, differential scanning calorimetry, thermogravimetry and infrared spectroscopy. The coordination compounds of MDetba with M = Rb, Cs and Tl crystallize in the orthorhombic space group P212121, but compound NH4Detba crystallizes in the triclinic space group P1¯. The MDetba structures were compared at the molecular and supramolecular levels. The Detba− ion in the NH4+ compound forms conformer (A) with two diethyl groups on one side of the ion ring, whereas the Detba− ion in the Rb(I), Cs(I) and Tl(I) compounds forms conformer (B) with two diethyl groups on different sides of the ring. The results of IR spectroscopy and thermal analysis are consistent with the X-ray data.

The Detba− ion (the ion of 1,3-diethyl-2-thiobarbituric acid) in the compounds MDetba (M = H+, Li+, Na+, K+, Tl+, Rb+, Cs+ and NH4+) exists in two different conformer types depending on the nature of the cation.Figure optionsDownload as PowerPoint slide