Abstract
In this study, three new 6-(arylthio)uracil derivatives, namely, 6-(phenylthio) pyrimidine- 2,4(1H, 3H)-dione (1), C10H8N2O2S; 6-(p-tolylthio)pyrimidine-2,4(1H,3H)-dione (2), C11H10N2O2S; and 6-(3,5-dimethylphenylthio)pyrimidine-2,4(1H,3H)-dione (3), C12H12N2O2S, have been synthesized. Single-crystal structures of these compounds reveal an invariant molecular tape contains alternate R-2(2)(8) synthons formed by N-H center dot center dot center dot O hydrogen bonds in 1 and 3. This alternate hydrogen-bonded pattern disappeared in 2; instead, a new synthon is generated. The lattice energy calculation suggests that the methyl-substituted derivatives (2 and 3) have high stabilization energy than compound 1. The electrostatic potential map reveals the difference in the accepting tendency of the carbonyl oxygen. The Hirshfeld surface and 2D-fingerprint plots analyses demonstrate that the major intermolecular interactions come from H center dot center dot center dot O contacts in 1, and these contacts were reduced due to the presence of methyl substitutions in 2 and 3. This reduction is compensated by the increase of the same amount of H center dot center dot center dot H contacts in these structures. Further, the PIXEL energy and DFT calculations at the M06-2X-D3/cc-pVTZ level of theory were used to characterize the dimeric topology formed in structures of 1-3. The intermolecular interaction energies of dimers calculated by the PIXEL method were compared with the B97D3/def2-TZVP level of approximation. Although these molecules' crystal packing is somewhat different, the energy frameworks show similarities on the respective crystal structure's shortest axis. Furthermore, the nature and strength of various noncovalent interactions such as N-H center dot center dot center dot O, C-H center dot center dot center dot O/S/pi, pi center dot center dot center dot pi, and a chalcogen bond of type C-S center dot center dot center dot O = C were evaluated using the Bader's quantum theory of atoms-in-molecules framework.