Correlations between 31P n.m.r. chemical shifts and structural parameters in crystalline inorganic phosphates

1986 ◽  
pp. 195 ◽  
Author(s):  
Anthony K. Cheetham ◽  
Nigel J. Clayden ◽  
Christopher M. Dobson ◽  
Roger J. B. Jakeman
Keyword(s):  
Chemical Shifts ◽  
Structural Parameters ◽  
Inorganic Phosphates

scholarly journals DFT STUDIES OF STRUCTURAL PARAMETERS, VIBRATIONAL FREQUENCIES AND NMR SPECTRA OF 3-(1H-BENZO[D]IMIDAZOL-1-YL)-N'-(TOSYLOXY)PROPANIMIDAMIDE

2021 ◽  
pp. 15-25
Author(s):  
E.M. Yergaliyeva ◽  
◽  
L.A. Kayukova ◽  
A.V. Vologzhanina ◽  
G.P. Baitursynova ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Structural Parameters ◽  
Correlation Coefficients ◽  
Biological Properties ◽  
Vibrational Frequencies ◽  
Substitution Product ◽  
Bond Angles ◽  
Bond Lengths ◽  
B3lyp Level

Amidoxime derivatives have practically valuable biological properties. We have previously obtained new spiropyrazolinium compounds by arylsulfo-chlorination of β-aminopropioamidoximes, but in case of β-(benzimidazol-1-yl)pro-pioamidoxime we have obtained O-substitution product – 3-(1H-benzo[d]imidazol-1-yl)-N'-(tosyloxy)pro-panimidamide. The aim of the work is predicting of structural parameters (bond lengths, bond angles), vibrational frequencies and NMR spectra of 3-(1H-benzo-[d]imidazol-1-yl)-N'-(tosyloxy)propanimidamide. The calculations were performed using Gaussian 09 package. Structural parameters and vibrational frequencies was calculated using DFT (B3LYP/B3PW91/WB97XD)/6-31G(d,p). 1H and 13C NMR was predicted using DFT B3LYP/6-31G(d,p)-GIAO in DMSO. All calculated values are in good agreement with experimental data. The calculated bond lengths and bond angles were compared with results of X-ray structural analysis. The best correlation coefficient was 0.981 (calcu-lations with B3LYP level). For bond angles, the best result was obtained with B3LYP level (0.990). For vibrational frequencies correlation coefficients between the calculated and experimental values were 0.997 (B3LYP), 0.996 (B3PW91) and 0.995 (WB97XD). The most accurate method was used for predic-ting NMR spectrum. The correlation coefficients between the experimental and calculated 1H and 13C chemical shifts were 0.949 and 0.999 respectively.

scholarly journals Structure, Vibrations, Molecular Orbitals, Reactivity Properties of 3-Trifluoromethylphenylchloroformate by FT-IR, FT-Raman, FT-NMR and DFT Studies

2019 ◽  
Vol 31 (8) ◽  
pp. 1737-1747
Author(s):  
V. Arjunan ◽  
S. Senthilkumari ◽  
S. Mohan
Keyword(s):  
Energy Gap ◽  
Chemical Shifts ◽  
Structural Parameters ◽  
Atomic Orbital ◽  
Molecular Orbitals ◽  
Basis Sets ◽  
Nucleophilic Attack ◽  
Orbital Energy ◽  
Total Electron Density ◽  
Total Electron

The geometry of 3-trifluoromethylphenylchloroformate (FMPCF) was optimized with B3LYP method using 6–311++G** and cc–pVTZ basis sets. The molecular structural parameters and thermodynamic properties of the compound have been determined. The vibrational frequencies of the fundamental modes of the compound have been precisely assigned, analyzed and the theoretical results were compared with the experimental data. The energies of important molecular orbitals of the compound are also evaluated from DFT method. The Frontier orbital energy gap (ELUMO–EHOMO) is found to be 6.2143 eV. The extreme limits of the electrostatic potential is +8.301e × 10–3 to –8.301e × 10–3 while the total electron density spreads between +3.835e × 10–2 to –3.835e × 10–2. 1H NMR and 13C NMR chemical shifts are measured and compared with their gauge independent atomic orbital (GIAO) calculated values. The n(O7) →π*(C13–O14) and π(C1–C6) →π*(C2–C3) transitions are best stablized with 48.40 and 21.03 kcal mol–1, respectively. In 3-trifluoromethylphenylchloroformate, the atoms C13 is favourable for electrophilic attack. The atoms C2 and C8 are more favourable for nucleophilic attack. The dual descriptors (Δfk, Δsk and Δωk) revealed that the order of nucleophilic attack is C1 > C4 > C2 > C8 > C5. Thus, the present investigation provides complete structure, vibrations and reactivity characteristics of the compound.

1-Iodoacétylènes. IV. Relations structure–réactivité pour la complexation des 1-iodoacétylènes substitués avec des bases de Lewis

1983 ◽  
Vol 61 (1) ◽  
pp. 135-138 ◽  
Author(s):  
Christian Laurence ◽  
Michèle Queignec-Cabanetos ◽  
Bruno Wojtkowiak
Keyword(s):  
Complex Formation ◽  
Triple Bond ◽  
Vibrational Frequency ◽  
Chemical Shifts ◽  
Structural Parameters ◽  
Equilibrium Constants ◽  
Lewis Acidity ◽  
Frequency Shifts ◽  
Substituent Constants ◽  
Substituted 1

The equilibrium constants for complex formation between the substituted 1-iodoacetylènes 1–8 and the vibrational frequency shifts induced by complex formation are related to the electronic substituent constants. The 13C chemical shifts of the triple bond are also useful structural parameters for predicting the Lewis acidity of iodoalkynes.

Computational (DFT and MP2) and spectral interpretations, normal coordinate analysis, force constants and barriers to internal rotations of Trimethylacetonitrile

2016 ◽  
Vol 15 (04) ◽  
pp. 1650034 ◽  
Author(s):  
Tarek A. Mohamed ◽  
Ibrahim A. Shaaban ◽  
Usama A Soliman ◽  
Lee D. Wilson
Keyword(s):  
Chemical Shifts ◽  
Structural Parameters ◽  
Energy Difference ◽  
High Energy ◽  
Normal Coordinate Analysis ◽  
Basis Set ◽  
Normal Coordinate ◽  
Methyl Torsion ◽  
Surface Scan ◽  
C Nmr

The Raman (3500[Formula: see text]cm[Formula: see text]100[Formula: see text]cm[Formula: see text] and IR spectra (4000[Formula: see text]cm[Formula: see text]400[Formula: see text]cm[Formula: see text] of liquid trimethylacetonitrile (C5H9N, TMA) have been obtained. In addition, the 1H and [Formula: see text]C NMR spectra of TMA were obtained in DMSO-[Formula: see text] and CDCl3. The staggered conformer (C[Formula: see text] was favored using MP2 and DFT(B3LYP/[Formula: see text]B97XD) quantum mechanical calculations utilizing a 6-311[Formula: see text]G(d,p) basis set. High energy difference estimates of 4534[Formula: see text]cm[Formula: see text]5338[Formula: see text]cm[Formula: see text] (12.96[Formula: see text]kcal/mol[Formula: see text]15.26[Formula: see text]kcal/mol) were predicted, along with three imaginary torsion frequencies for the eclipsed conformer, therefore considered a transition state. The 1H and [Formula: see text]C NMR chemical shifts were predicted with B3LYP and [Formula: see text]B97XD methods using the GIAO approximation and 6-311[Formula: see text]G(d,p) basis set. B3LYP frequencies calculation is favored herein owing to the relatively good compilation with the experimental measurements. The computed structural parameters are well correlated to those reported from electron diffraction and microwave studies. Moreover, the [Formula: see text]C[Formula: see text]H coupling constant was estimated and found consistent with that observed for the sample dissolved in DMSO-[Formula: see text]/CDCl3 solvents. Using the observed methyl torsion at 266[Formula: see text]cm[Formula: see text] in gas phase and the kinetic parameter F number, a potential function (V[Formula: see text] of [Formula: see text][Formula: see text]cm[Formula: see text]([Formula: see text][Formula: see text]kcal/mol) was obtained, this barrier to internal rotation is well correlated to 1527[Formula: see text]cm[Formula: see text] (4.37[Formula: see text]kcal/mol) predicted from MP2/6-311[Formula: see text]G(d,p) potential surface scan. Aided by the predicted wavenumbers and their IR intensity/Raman activity, the observed IR/Raman bands were intensively discussed and therefore assigned to their corresponding fundamentals, in agreement with novel normal coordinate analysis and potential energy distributions (PEDs).

A chromium carbene (OC)5Cr=C(OEt)(–C≡C–Ph): Quantum mechanical study of molecular structure, HOMO–LUMO analysis, IR spectroscopy, natural bond orbital analysis

2015 ◽  
Vol 14 (03) ◽  
pp. 1550022 ◽  
Author(s):  
Reza Ghiasi
Keyword(s):  
Electron Density ◽  
Chemical Shifts ◽  
Structural Characteristics ◽  
Structural Parameters ◽  
Atomic Orbital ◽  
Polarizable Continuum Model ◽  
Topological Parameters ◽  
H Nmr ◽  
Quantum Mechanical Study ◽  
Chromium Carbene

In this work, the structural, electronic properties, 13 C and 1 H NMR parameters and first hyperpolarizability of a chromium carbene ( OC )5 Cr = C ( OEt )(– C ≡ C – Ph ) complex were theoretically computed in gas phase and different solvents. Also, the solvent effect on structural parameters, frontier orbital energies, – C ≡ C – and C ≡ O stretching frequencies of complex has been carried out based on polarizable continuum model (PCM). The results indicate that the polarity of solvents has played a significant role on the structures and properties of complex. 1 H and 13 C NMR chemical shifts were calculated by using the gauge-independent atomic orbital (GIAO) method. In analyzing the structural characteristics of this structure, Cr – CO and Cr – C carbene bonds were identified and characterized in detail by topological parameters such as electron density ρ(r) and Laplacian of electron density ∇2ρ(r) from Bader's atom in molecules theory.

scholarly journals Evaluation of the ONIOM(B3PW91:HF) hybrid method for modeling butyltin chlorides

2013 ◽  
Vol 11 (8) ◽  
pp. 1257-1263 ◽  
Author(s):  
Piotr Matczak
Keyword(s):  
Conformational Analysis ◽  
Hybrid Method ◽  
Chemical Shifts ◽  
Structural Parameters ◽  
Computational Cost ◽  
Molecular Properties ◽  
Small Decrease ◽  
Significant Saving ◽  
Careful Choice ◽  
119Sn Nmr

AbstractThe ONIOM(B3PW91:HF) hybrid method has been evaluated for the purposes of modeling butyltin chlorides, XnSnCl4-n (X = n-butyl, sec-butyl, isobutyl, tert-butyl; n = 1, 2, 3). Three different partitioning schemes of a molecule within ONIOM(B3PW91:HF) were taken into account. For each of these partitioning schemes, conformational analyses of the XnSnCl4-n molecules were performed and then several molecular properties of the resulting rotamers were calculated. The values of molecular properties obtained by ONIOM(B3PW91:HF) were compared in a statistical manner with the reference values calculated by B3PW91. A careful choice of partitioning scheme for XnSnCl4-n allowed ONIOM(B3PW91:HF) to achieve a significant saving in computational cost, together with a relatively small decrease in the accuracy of the XnSnCl4-n molecular properties routinely obtained from conformational analysis (structural parameters, etc.). Unfortunately, the hybrid method turned out to be ineffective in reproducing the 1H, 13C and 119Sn NMR chemical shifts in XnSnCl4-n accurately.

ELECTRONIC AND STRUCTURAL PARAMETERS OF PHOSPHORUS–OXYGEN BONDS IN INORGANIC PHOSPHATE CRYSTALS

2008 ◽  
Vol 15 (04) ◽  
pp. 391-399 ◽  
Author(s):  
V. V. ATUCHIN ◽  
V. G. KESLER ◽  
N. V. PERVUKHINA
Keyword(s):  
Binding Energy ◽  
Bond Length ◽  
Chemical Bond ◽  
Linear Dependence ◽  
Inorganic Phosphate ◽  
Structural Parameters ◽  
Complex Oxide ◽  
Energy Difference ◽  
X Ray ◽  
Inorganic Phosphates

Wide set of experimental results on binding energy of photoelectrons emitted from P 2 p , P 2 s , and O 1 s core levels has been observed for inorganic phosphate crystals and the parameters were compared using energy differences Δ( O 1 s - P 2 p ) and Δ ( O 1 s - P 2 s ) as most robust characteristics. Linear dependence of the binding energy difference on mean chemical bond length L( P – O ) between phosphorus and oxygen atoms has been found. The functions are of the forms: Δ ( O 1 s - P 2 p ) ( eV ) = 375.54 + 0.146 · L( P – O ) ( pm ) and Δ ( O 1 s - P 2 s ) ( eV ) = 320.77 + 0.129 · L( P – O ) ( pm ). The dependencies are general for inorganic phosphates and may be used in quantitative component analysis of X-ray photoemission spectra of complex oxide compounds including functional groups with different coordination of P and O atoms.

Simulation of 13C N.M.R. Spectra of Nitrogen-Containing Aromatic Compounds

1995 ◽  
Vol 48 (7) ◽  
pp. 1267 ◽  
Author(s):  
M Jalaliheravi ◽  
M Moosavi
Keyword(s):  
Standard Deviation ◽  
Linear Regression ◽  
Aromatic Compounds ◽  
Chemical Shifts ◽  
Structural Parameters ◽  
Semiempirical Method ◽  
Molecular Structures ◽  
Stepwise Multiple Linear Regression ◽  
Methyl Derivatives ◽  
Geometric Descriptors

The 13C n.m.r. spectra of a series of nitrogen-containing aromatic compounds have been simulated by using parametric techniques. The observed chemical shifts were related to numerically encoded structural parameters, called descriptors. The electronic and geometric descriptors were calculated after optimization of the molecular structures by using the MNDO semiempirical method. Subsequently, the method of stepwise, multiple linear regression was used to calculate coefficients relating the descriptors to the observed chemical shifts. This study involves 32 compounds such as pyridine, pyrimidine, triazine, pyridazine, and their methyl derivatives. Plotting of experimental against calculated chemical shifts for 23 carbon centres in the prediction set of five compounds shows a standard deviation of 1.41 ppm and a correlation coefficient of 0.999.

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