Theoretical studies of molecular structure and vibrational spectra of O-ethyl benzoylthiocarbamate

Crystal structure of O-hexyl benzoylcarbamothioate, C14H19NO2S

C14H19NO2S, monoclinic, P21/c (no. 14), a = 8.6849(10) Å, b = 18.740(2) Å, c = 10.0465(12) Å, β = 112.845(3)°, V = 1506.9(3) Å3, Z = 4, R gt(F) = 0.0685, wR ref(F 2) = 0.2023, T = 293(2) K.

An intramolecular 1,5-chalcogen bond on the conformational preference of carbonyl thiocarbamate species

Two closely related carbamothioates were prepared by the reaction of benzoyl isothiocyanates and methanol. The crystal structures show the occurrence of 1,5-O⋯O intramolecular short distance that determines the conformational preference.

Understanding the conformational changes and molecular structure of furoyl thioureas upon substitution

1-Acyl thioureas [R¹C(O)NHC(S)NR²R³] are shown to display conformational flexibility depending on the degree of substitution at the nitrogen atom. The conformational landscape and structural features for two closely related thioureas having R¹=2-furoyl have been studied. The un-substituted 2-furoyl thiourea (I) and its dimethyl analogue, i.e. 1-(2-furoyl)-3,3-dimethyl thiourea (II), have been synthesized and fully characterized by spectroscopic (FT-IR, ¹H and ¹³C NMR) and elemental analysis. According to single crystal X-ray diffraction analysis, compounds I and II crystallize in the monoclinic space group P21/c. In the compound I, the trans-cis geometry of the almost planar thiourea unit is stabilized by intramolecular NH⋯OC hydrogen bond between the H atom of the cis thioamide and the carbonyl O atom. In compound II, however, the acyl thiourea group is non-planar, in good agreement with the potential energy curve computed at the B3LYP/6-31+G(d,p) level of approximation. Centrosymmetric dimers generated by intermolecular NH⋯SC hydrogen bond forming R₂²(8) motif are present in the crystals. Intermolecular interactions have been rationalized in terms of topological partitions of the electron distributions and Hirshfeld surface analysis, which showed the occurrence of S⋯H, O⋯H and H⋯H contacts that display an important role to crystal packing stabilization of both thiourea derivatives.

Synthesis, X-ray crystal structure, thermal behavior and spectroscopic analysis of 1-(1-naphthoyl)-3-(halo-phenyl)-thioureas complemented with quantum chemical calculations

Two novel 1-(1-naphthoyl)-3-(halo-phenyl) substituted thioureas, namely 1-(1-naphthoyl)-3-(2,4-di-fluoro-phenyl)-thiourea (1) and 1-(1-naphthoyl)-3-(3-chloro-4-fluoro-phenyl)-thiourea (2), were synthesized and fully characterized. The X-ray crystal and molecular structures have been determined resulting in a planar acylthiourea group, with the C=O and C=S adopting a pseudo-antiperiplanar conformation. An intramolecular N-H⋯O=C hydrogen bond occurs between the thioamide and carbonyl groups. The crystal packing of both compounds is characterized by extended intermolecular N-H⋯S=C and N-H⋯O=C hydrogen-bonding interactions involving the acylthiourea moiety. Compound 2 is further stabilized by π-stacking between adjacent naphthalene and phenyl rings. The thermal behavior, as well as the vibrational properties, studied by infrared and Raman spectroscopy data complemented by quantum chemical calculations at the B3PW91/6-311++G(d,p) support the formation of these intra- and intermolecular hydrogen bonds. Furthermore, the UV-Vis spectrum is interpreted in terms of TD-DFT quantum chemical calculations with the shapes of the simulated absorption spectra in good accordance with the experimental data.

Bipodal benzoylthiocarbamic acid esters: crystal and molecular structures of R = Et (a polymorph), and of a binuclear Cu(I) complex, R = iPr

The crystal and molecular structure of a second polymorph (P21/n) of [1,4-ROC(=S)N(H)C(=O)C6H4C(=O)N(H)C(=S)OR], R = Et, is shown to have inversion symmetry and to have a more twisted conformation than the previously reported P43212 form which has 2-fold symmetry. Despite utilising equivalent atoms in forming intermolecular interactions, very distinct crystal packing patterns are observed. Crystal characteristics and theory (DFT) are consistent with the P43212 form being more stable, a conclusion correlated with the observation that this form is the overwhelming majority of the sample (PXRD). An analysis of a binuclear copper(I) complex containing the R = iPr analogue, reveals the neutral ligand to bind via the thione-S atom resulting in a distorted ClP2S tetrahedral geometry.

The molecular structure and vibrational spectra of N-(3-tert-butyl-2-hydroxybenzylidene)-2,6-diphenyl-4-hydroxyaniline

The molecular structure, vibrational frequencies and intensities of N-(3-tert-butyl-2-hydroxybenzylidene)-2,6-diphenyl-4-hydroxyaniline were calculated by the Density Functional Theory methods (BLYP, B3PW91 and B3LYP) using the 6-31G(d,p) basis set. The calculated geometric parameters were compared to the corresponding X-ray structure of the title compound. The comparison of the theoretical and experimental geometry of the title compound shows that the X-ray parameters fairly well reproduce the geometry of optimized by B3LYP method (r=0.9825). The harmonic vibrations computed for this compound by the B3LYP/6-31G(d,p) method are in good agreement with the observed IR and Raman spectral data. The root mean square values error of the observed and calculated IR bands are found to be 9.80, 9.40 and 8.42 for B3LYP, B3PW91 and BLYP/6-31G(d,p) methods, respectively. Theoretical vibrational spectra of the title compound were interpreted by means of PEDs using the SQM 2.0 program. A general better performance of the investigated methods was calculated by PAVF 1.0 program.

Synthesis, structural and vibrational properties of 1-(adamantane-1-carbonyl)-3-halophenyl thioureas

1-(Adamantane-1-carbonyl)-3-(2,4-dichlorophenyl)thiourea (1) and 1-(adamantane-1-carbonyl)-3-(2-bromo-4,6-difluorophenyl)thiourea (2) were synthesized by the reaction of adamantane-1-carbonyl chloride with ammonium thiocyanate to afford the adamantane-1-carbonylisothiocyanate in situ followed by treatment with suitable halogenated anilines. The structures of the products were established by elemental analyses, Fourier transform infrared spectroscopy (FTIR), (1)H, (13)C nuclear magnetic resonance (NMR), mass spectroscopy and single crystal X-ray diffraction study. Bond lengths and angles show the usual values. All of three condensed cyclohexane rings of the adamantane residues adopt the usual chair conformation. The molecular conformation of 1 and 2 is stabilized by an intramolecular (NH⋯OC) hydrogen bond which forms a pseudo-six-membered ring. Structural features have been complemented with the joint analysis of the FTIR and FT-Raman spectra along with quantum chemical calculations at the B3LYP/6-311++G level.

Vibrational Spectroscopy Investigation Using Ab Initio and Density Functional Theory Analysis on the Structure oftert-Butyl 3a-Chloroperhydro-2,6a-epoxyoxireno[e]isoindole-5-carboxylate

The molecular structure, vibrational frequencies, and infrared intensities of thetert-butyl 3a-chloroperhydro-2,6a-epoxyoxireno[e]isoindole-5-carboxylate were calculated by the HF and DFT (BLYP and B3LYP) methods using 6-31G(d) and 6-31G(d,p) basis sets. The FT infrared spectrum of the solid sample was measured under standard condition. We obtained two stable conformers for the title compound; however Conformer 1 is approximately 0.2 kcal/mol more stable than the Conformer 2. The comparison of the theoretical and experimental geometry of the title compound shows that the X-ray parameters fairly well reproduce the geometry of Conformer 2. Comparison of the observed fundamental vibrational frequencies of the title molecule and calculated results by HF and DFT methods indicates that B3LYP is superior for molecular vibrational problems. The harmonic vibrations computed by the B3LYP/6-31G(d,p) method are in a good agreement with the observed IR spectral data. Theoretical vibrational spectra of the title compound were interpreted by means of potential energy distributions (PEDs) using VEDA 4 program.

Nonplanar property study of antifungal agent tolnaftate-spectroscopic approach

Vibrational analysis of the thionocarbamate fungicide tolnaftate which is antidermatophytic, antitrichophytic and antimycotic agent, primarily inhibits the ergosterol biosynthesis in the fungus, was carried out using NIR FT-Raman and FTIR spectroscopic techniques. The equilibrium geometry, various bonding features, harmonic vibrational wavenumbers and torsional potential energy surface (PES) scan studies have been computed using density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA.4 program. Vibrational spectra, natural bonding orbital (NBO) analysis and optimized molecular structure show the clear evidence for electronic interaction of thionocarbamate group with aromatic ring. Predicted electronic absorption spectrum from TD-DFT calculation has been compared with the UV-vis spectrum. The Mulliken population analysis on atomic charges and the HOMO-LUMO energy were also calculated. Vibrational analysis reveals that the simultaneous IR and Raman activation of the C-C stretching mode in the phenyl and naphthalene ring provide evidence for the charge transfer interaction between the donor and acceptor groups and is responsible for its bioactivity as a fungicide.

Properties of the Michael's adducts of the substituted 2-amino-5-oxonitriles

A series of five substituted 2-amino-5-oxonitriles, obtained by the Michael reaction have been designed, synthesised, isolated and spectroscopically and structurally elucidated by means of single crystal X-ray diffraction, linear-polarized infrared (IR-LD) and UV-spectroscopy, (1)H NMR, mass spectrometry and thermal methods. Theoretical quantum chemical calculations were carried out, thus supporting the experimental optical properties and electronic structure of compounds studied.

Hydrogen-bonding patterns in two aroylthiocarbamates and two aroylimidothiocarbonates

In O-ethyl N-benzoylthiocarbamate, C(10)H(11)NO(2)S, the molecules are linked into sheets by a combination of two-centre N-H...O and C-H...S hydrogen bonds and a three-centre C-H...(O,S) hydrogen bond. A combination of two-centre N-H...O and C-H...O hydrogen bonds links the molecules of O-ethyl N-(4-methylbenzoyl)thiocarbamate, C(11)H(13)NO(2)S, into chains of rings, which are linked into sheets by an aromatic pi-pi stacking interaction. In O,S-diethyl N-(4-methylbenzoyl)imidothiocarbonate, C(13)H(17)NO(2)S, pairs of molecules are linked into centrosymmetric dimers by pairs of symmetry-related C-H...pi(arene) hydrogen bonds, while the molecules of O,S-diethyl N-(4-chlorobenzoyl)imidothiocarbonate, C(12)H(14)ClNO(2)S, are linked by a single C-H...O hydrogen bond into simple chains, pairs of which are linked by an aromatic pi-pi stacking interaction to form a ladder-type structure.

The molecular structure and vibrational spectra of N-(2,2-diphenylacetyl)-N'-(naphthalen-1yl)-thiourea by Hartree-Fock and density functional methods

N-(2,2-Diphenylacetyl)-N'-(naphthalen-1yl)-thiourea (PANT) has been synthesized and characterized by elemental analysis, IR spectroscopy and (1)H NMR spectroscopy. The crystal and molecular structure of the title compound has been determined from single crystal X-ray diffraction data. It crystallizes in the triclinic space group P-1, Z=2 with a=10.284(2)A, b=10.790(2)A, c=11.305(2)A, alpha=64.92(3) degrees , beta=89.88(3) degrees , gamma=62.99(3) degrees , V=983.7(3)A(3) and D(calc)=1.339Mg/m(3). The molecular structure, vibrational frequencies and infrared intensities of PANT were calculated by the Hartree-Fock and density functional theory methods (BLYP and B3LYP) using the 6-31G* basis set. The calculated geometric parameters were compared to the corresponding X-ray structure of the title compound. We obtained 22 stable conformers for the title compound; however Conformer 1 is approximately 9.53kcal/mol more stable than Conformer 22. The comparison of the theoretical and experimental geometry of the title compound shows that the X-ray parameters fairly well reproduce the geometry of Conformer 17. The harmonic vibrations computed for this compound by the B3LYP/6-31G* method are in good agreement with the observed IR spectral data. Theoretical vibrational spectra of the title compound were interpreted by means of PEDs using the VEDA 4 program. A general better performance of the investigated methods was calculated by PAVF 1.0 program.

4-Bromo-N-(di-n-propyl-carbamothioyl)-benzamide

The synthesis of the title compound, C₁₄H₁₉BrN₂OS, involves the reaction of 4-bromo­benzoyl chloride with potassium thio­cyanate in acetone followed by condensation of the resulting 4-bromo­benzoyl isothio­cyanate with di-n-propyl­amine. Typical thio­urea carbonyl and thio­carbonyl double bonds, as well as shortened C—N bonds, are observed in the title compound. The short C—N bond lengths in the centre of the mol­ecule reveal the effects of resonance in this part of the mol­ecule. The asymmetric unit of the title compound contains two crystallographically independent mol­ecules, A and B. There is very little difference between the bond lengths and angles of these mol­ecules. In mol­ecule B, one di-n-propyl group is twisted in a −anti­periplanar conformation with C—C—C—H = −179.1 (3)° and the other adopts a −synclinal conformation with C—C—C—H = −56.7 (4)°; in mol­ecule A the two di-n-propyl groups are twisted in + and −anti­periplanar conformations, with C—C—C—H = −179.9 (3) and 178.2 (3)°, respectively. In the crystal, the mol­ecules are linked into dimeric pairs via pairs of N—H⋯S hydrogen bonds.

4-Bromo-N-(diethyl-carbamothio-yl)-benzamide

The synthesis of the title compound, C₁₂H₁₅BrN₂OS, involves the reaction of 4-bromo­benzoyl chloride with potassium thio­cyanate in dry acetone, followed by condensation of 4-bromo­benzoyl isothio­cyanate with diethyl­amine. The carbonyl and thio­carbonyl bond lengths indicate that these correspond to double bonds. The short C—N bond lengths reveal the effects of resonance in this part of the mol­ecule. The conformation of the mol­ecule with respect to the thio­carbonyl and carbonyl units is twisted, with torsion angles of −5.7 (3) and 87.2 (2)°. The N atom of the diethyl­amine group is sp²-hybridized: the sum of the angles around the N atom is 359.97 (14)°. The two diethyl groups are twisted in + and − anti­periplanar conformations with angles of −179.89 and 179.92°. In the crystal structure, the mol­ecules form infinite chains via an inter­molecular N—H⋯O inter­action.

Antimicrobial activity of some thiourea derivatives and their nickel and copper complexes

Five thiourea derivative ligands and their Ni(2+) and Cu(2+) complexes have been synthesized. The compounds were screened for their in vitro anti-bacterial activity using Gram-positive bacteria (two different standard strains of Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Streptococcus pyogenes, Bacillus cereus) and Gram-negative bacteria (Esherichia coli, Pseudomonas aeruginosa, Enterobacter cloacae, Proteus vulgaris, Enterobacter aerogenes) and in vitro anti-yeast activity (Candida albicans, Candida krusei, Candida glabrata, Candida tropicalis, Candida parapsilosis). The minimum inhibitory concentration was determined for all ligands and their complexes. In vitro anti-yeast activity of both ligands and their metal complexes is greater than their in vitro anti-bacterial activity. The effect of the structure of the investigated compounds on the antimicrobial activity is discussed.

4-Chloro-N-[N-(6-methyl-2-pyrid-yl)car-bamo-thio-yl]benzamide

In the title compound, C(14)H(12)ClN(3)OS, the short exocyclic N-C bond lengths indicate resonance in the thiourea part of the mol-ecule. The title compound is stabilized by an intra-molecular N-H⋯N hydrogen bond, which results in the formation of a six-membered ring. In addition, it shows a synperiplanar conformation between the thio-carbonyl group and the pyridine group. Inter-molecular N-H⋯S and C-H⋯O inter-actions are also present.

Vibrational spectrum and assignments of 2-(4-methoxyphenyl)-1H-benzo[d]imidazole by ab initio Hartree-Fock and density functional methods

The room temperature attenuated total reflection Fourier transform infrared spectrum of the 2-(4-methoxyphenyl)-1H-benzo[d]imidazole has been recorded with diamond/ZnSe prism. The conformational behaviour, structural stability of optimized geometry, frequency and intensity of the vibrational bands of the title compound were investigated by utilizing ab initio calculations with 6-311G** basis set at HF, B3LYP, BLYP, B3PW91 and mPW1PW91 levels. The harmonic vibrational frequencies were calculated and scaled values have been compared with experimental IR spectrum. The observed and the calculated frequencies are found to be in good agreement. The theoretical vibrational spectra of the title compound were interpreted by means of potential energy distributions using VEDA 4 program. Furthermore, the optimal uniform scaling factors calculated for the title compound are 0.9120, 0.9596, 0.9660, 0.9699, and 0.9993 for HF, mPW1PW91, B3PW91, B3LYP and BLYP methods, respectively.

Vibrational spectroscopy investigation using ab initio and density functional theory analysis on the structure of 5-chloro-10-oxa-3-thia-tricyclo[5.2.1.0(1,5)]dec-8-ene-3,3-dioxide

The IR spectra of 5-chloro-10-oxa-3-thia-tricyclo[5.2.1.0(1,5)]dec-8-ene-3,3-dioxide (COTDO) has been recorded in the region 4000-525cm(-1). The optimized molecular geometry, frequency and intensity of the vibrational bands of COTDO in the ground state has been calculated using the Hartree-Fock and density functional using Becke's three-parameter hybrid method with the Lee, Yang, and Parr correlation functional methods with 6-31G(d,p) and 6-311G(d,p) basis sets. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental IR spectra. The calculated geometrical parameters and harmonic vibrations are predicted in a very good agreement with the experimental data. The theoretical vibrational spectra of the title compound were interpreted by means of potential energy distributions (PEDs) using VEDA 4 program. With the help of this modern technique we were able to complete the assignment of the vibrational spectra of the title compound.

The molecular structure and vibrational spectra of 2-chloro-N-(diethylcarbamothioyl)benzamide by Hartree-Fock and density functional methods

2-Chloro-N-(diethylcarbamothioyl)benzamide (C(12)H(15)ClN(2)OS) has been synthesized and characterized by elemental analysis and IR spectroscopy. The crystal and molecular structure of the title compound has been determined from single crystal X-ray diffraction data. It crystallizes in the orthorhombic space group Pbca, Z=8 with a=9.581(3)A, b=9.992(3)A, c=26.640(8)A, V=2550.5(13)A(3) and D(calc)=1.410 Mg/m(3). The molecular geometry and vibrational frequencies of 2-chloro-N-(diethylcarbamothioyl)benzamide in the ground state have been calculated using the Hartree-Fock and density functional using Becke's three-parameter hybrid method with the Lee, Yang and Parr correlation functional (B3LYP) methods with 3-21G and 6-31G(d) basis sets. The calculated geometric parameters were compared to the corresponding X-ray structure of the title compound. The raw B3LYP frequencies approximate the experimental data much better than the results of Hartree-Fock. The scaled B3LYP/6-31G(d) results were more reliable than those obtained using the B3LYP/3-21G method with the mean absolute deviation about 13.7 cm(-1). On the basis of the comparison between calculated and experimental results, assignments of fundamental vibrational modes were examined.