Abstract
The synthesis of C-2-symmetrical bis(beta-enamino-pyran-2,4-dione) derivative 3 connected via 1,6-hexylene linker was reported for the first time. X-ray structures and Hirshfeld studies of the new bis- beta-enamino-pyran-2,4-dione derivative 3 along with two structurally related pyran-2,4-dione derivatives 2a,b were discussed. A comparative analysis of the different intermolecular contacts affecting the crystal stability was presented. Generally, the H horizontal ellipsis H, O horizontal ellipsis H, and H horizontal ellipsis C interactions are common in all compounds and are considered the most abundant contacts. In addition, DFT calculations were used to compute the electronic properties as well as the H-1 and C-13 NMR spectra of the studied systems. All compounds (except 3) are polar where 2a (3.540 Debye) has a higher dipole moment than 2b (2.110 Debye). The NMR chemical shifts were calculated and excellent correlations between the calculated and experimental data were obtained (R-2 = 0.93-0.94).