Abstract
The gem-aminals of 1,2-dimorpholinoethane (1) and 1-morpholino-3-morpholinium bromide propane (2) were synthesized by reaction of two molar ratio of morpholine with the halogenating agents in the presence of basic condition (K2CO3) in acetone at room temperature (RT) overnight. The structures of the centro-symmetric compound 1 and the morpholinium salt derivative 2 were assigned unambiguous by single crystal X-ray diffraction analysis and compared with the 1,2-di(pyrrolidin-1-yl)ethane 3 and 1,2-di(piperidin-1-yl)ethane 4. The 1,2-dimorpholinoethane molecule has a center of symmetry at the midpoint of the C-C bond of the ethyl moiety leading to two equivalent halves. It crystallized in monoclinic crystal system and P2(1)/n space group, while the unit cell parameters are determined to be a = 6.0430(3), b = 8.0805(3), c = 11.1700(4) angstrom, and beta = 97.475(2)degrees with unit cell volume of 540.80(4) angstrom(3) and Z = 2 at 170(2) K. The less symmetric analogue 2 crystallized in the lower space group P2(1) with unit cell parameters of a = 6.37450(10), b = 11.1378(2), c = 9.6549(2) angstrom, and beta = 93.358(2)degrees, while the unit cell volume is 684.30(2)angstrom(3) at 120(2) K. Using Hirshfeld analysis, the molecules of 1 are mainly packed by weak N horizontal ellipsis H (4.2%), O horizontal ellipsis H (16.8%), and H horizontal ellipsis H (79.0%) interactions. In contrast, the molecules of 2 are packed by significantly short O horizontal ellipsis H (14.4%) and Br horizontal ellipsis H (11.6%) interactions in addition to the relatively long H horizontal ellipsis H (73.3%) interactions. DFT calculations predicted the molecular geometry of the studied compounds showing a good agreement with the experimental X-ray structures. Due to symmetry considerations, compounds 1, 3, and 4 are nonpolar with zero dipole moment, while the less symmetric molecule 2 has a dipole moment of 6.914 Debye. Their electronic aspects, such as natural population charges, HOMO, and LUMO energies as well as the corresponding reactivity descriptors, were also calculated and discussed.