Layered crystal structure, conformational and vibrational properties of 2,2,2-trichloroethoxysulfonamide: an experimental and theoretical study

A detailed exploration of intermolecular interactions in 4-(4-dimethylaminobenzylideneamino)-N-(5-methyl-3-isoxazolyl)benzenesulfonamide and related Schiff bases: Crystal structure, spectral studies, DFT methods, Pixel energies and Hirshfeld surface analysis

The Schiff base of the title has been synthesized and its crystal structure determined by single-crystal X-ray diffraction. The compound was characterized by IR, Raman, ¹H NMR, ¹³C NMR and electronic absorption spectra. DFT calculations provide the quantum chemical basis for the observed molecular conformation. A study of intermolecular interactions of the title compound is compared with seven other closely related structures and reveals that molecules in most of the compounds are linked by a cooperative effect of strong and weak hydrogen bonds, CH^…π, and π^…π stacking interactions, and also lp^…π contacts. Lattice energy calculations indicate that the dispersion component is the major contribution, with the coulombic term playing a significant role in the total energy. Interaction energies for molecular pairs involving NH···N bonds indicate a dominant contribution to packing stabilization coming from coulomb component. Hirshfeld surfaces and 2D-fingerprint plots allowed us to visualize different intermolecular contacts and its relative contributions to total surface in each compound. The analysis of electrostatic potential (ESP) maps correlates well with the computed energies providing evidences on the dominant electrostatic nature of NH···N and NH···O interactions.

Gas-phase structure of 2,2,2-trichloroethyl chloroformate studied by electron diffraction and quantum-chemical calculations

The molecular structure and conformational properties of 2,2,2-trichloroethyl chloroformate, ClC(O)OCH2CCl3 were determined experimentally using gas-phase electron diffraction (GED) and theoretically based on quantum-chemical calculations at the MP2 and DFT levels of theory. Further experimental measurements such as UV-visible, IR and Raman spectroscopy were complemented with the corresponding theoretical studies. All experimental results and calculations confirm the presence of two conformers namely anti-gauche (C1 symmetry) and anti-anti (Cs symmetry). The conformational preference was rationalised by NBO and AIM analyses. Molecular properties such as ionisation potential, electronegativity, chemical potential, chemical hardness and softness were deduced from HOMO-LUMO analyses. The TD-DFT approach was applied to assign the electronic transitions observed in the UV-visible spectrum. A detailed interpretation of the infrared and Raman spectra of the title compound are reported. Using calculated frequencies as a guide, IR and Raman spectra also provide evidence for the presence of both C1 and Cs conformers.

Quantum chemical studies on molecular structure, spectroscopic (IR, Raman, UV-Vis), NBO and HOMO-LUMO analysis of 1-benzyl-3-(2-furoyl) thiourea

Vibrational and electronic spectra for 1-benzyl-3-(2-furoyl) thiourea were calculated by using density functional method (B3LYP) with different basis sets. The complete assignment of all vibrational modes was performed on basis of the calculated frequencies and comparing with the reported IR and Raman spectra for that thiourea derivative. UV-visible absorption spectra of the compound dissolved in methanol were recorded and analyzed using time dependent density functional theory (TD-DFT). The calculated values for the geometrical parameters of the title compound are consistent with the ones reported from XRD studies. The stability of the molecule, related to hyper-conjugative interactions, and electron delocalization were evaluated using natural bond orbital (NBO) analysis. Intra-molecular interactions were studied by AIM approach. The HOMO and LUMO analysis are used to determine the charge transfer within the molecule. Molecular electrostatic potential map was performed by the DFT method.

Structural, vibrational and electronic characterization of 1-benzyl-3-furoyl-1-phenylthiourea: an experimental and theoretical study

The compound 1-benzyl-3-furoyl-1-phenylthiourea was synthesized and characterized through IR and Raman spectroscopy and its molecular structure was determined.

DFT calculations of structure and vibrational properties of 2,2,2-trichloroethylacetate, CH(3)CO(2)CH(2)CCl(3)

The molecular structure and conformational properties of 2,2,2-trichloroethylacetate, CH(3)CO(2)CH(2)CCl(3), were determined by ab initio (MP2) and DFT quantum chemical calculations at different levels of theory. The theoretical study was complemented with experimental measurements such as IR and Raman spectroscopy. The experimental and calculations confirm the presence of two conformers, one with anti, gauche conformation (C1 symmetry) and another with anti, anti form (Cs symmetry). The conformational preference was studied using the total energy scheme, NBO and AIM analysis. The infrared spectra of CH(3)CO(2)CH(2)CCl(3) are reported in the liquid and solid phases and the Raman spectrum in liquid phase. Using calculated frequencies as a guide, evidence for both C1 and Cs conformers is obtained in the IR and Raman spectra.