Charge distributions and chemical effects. XXXI. Molecular energies of ethylenic compounds

1983 ◽  
Vol 61 (1) ◽  
pp. 197-205 ◽  
Author(s):  
M.-T. Béraldin ◽  
S. Fliszâr
Keyword(s):  
Zero Point ◽  
Enthalpies Of Formation ◽  
Average Deviation ◽  
Bond Forming ◽  
Chemical Effects ◽  
Nuclear Magnetic Resonance Spectra ◽  
Energy Formula ◽  
Standard Enthalpies Of Formation ◽  
Vibrational Energies ◽  
Proper Consideration

The energy formula describing bond contributions in terms of the charges carried by the bond-forming atoms is applied to ethylenic compounds. It is shown in what manner σ and π electrons can be treated within the framework of the bond energy theory giving the atomization energy of the vibrationless molecule at 0 K. Proper consideration of zero-point and thermal vibrational energies leads to standard enthalpies of formation. These calculations, which are carried out on the basis of, 13C nuclear magnetic resonance spectra, agree with their experimental counterparts, within experimental uncertainties (~0.3 kcal mol−1 average deviation).

Charge distributions and chemical effects. XXIV. On the role of vibrational energies in determining molecular stabilities

1981 ◽  
Vol 59 (9) ◽  
pp. 1381-1387 ◽  
Author(s):  
Sándor Fliszár ◽  
J.-L. Cantara
Keyword(s):  
Conformational Changes ◽  
Vibrational Energy ◽  
Heat Content ◽  
Zero Point ◽  
Enthalpies Of Formation ◽  
Chemical Binding ◽  
Nuclear Magnetic Resonance Spectra ◽  
Molecular Stability ◽  
Coulomb Type ◽  
Vibrational Energies

A simple equation has been derived for calculating accurate ZPE + HT − H0 (zero-point and heat content) energies of saturated hydrocarbons from their enthalpies of formation and carbon-13 nuclear magnetic resonance spectra. Applications to conformational analysis indicate a near invariance of vibrational energies with respect to chair–boat conformational changes of the cyclohexane ring, the loss in molecular stability arising then from a weakening of the chemical binding due to a reorganization of the electronic charges. The origin of the destabilizing effect of butane gauche interactions is found, in the cyclohexane series, in a weakening of the chemical binding (∼1.85 kcal/mol) which is partially compensated by a lowering (∼0.85 kcal/mol) vibrational energy, thus offering an explanation for the loss in molecular stability of ∼1.00 kcal/mol for one gauche interaction without invoking Coulomb-type repulsions between non-bonded atoms. Calculated enthalpies of formation are presentd for a number of cycloalkanes.

Charge distributions and chemical effects. XLV. Graphite

1988 ◽  
Vol 66 (10) ◽  
pp. 2631-2633 ◽  
Author(s):  
Andrea Peluso ◽  
Sándor Fliszár
Keyword(s):  
Heat Content ◽  
Zero Point ◽  
Van Der Waals Interactions ◽  
Bond Energies ◽  
Net Charge ◽  
Point Energy ◽  
Bond Forming ◽  
Experimental Heat ◽  
Chemical Effects ◽  
Debye Temperatures

The zero point energy of graphite, [Formula: see text], is deduced from Debye's theory by separating the lattice vibrations into two approximately independent parts, with Debye temperatures [Formula: see text] (in plane) and [Formula: see text] (perpendicular). A balanced evaluation gives [Formula: see text]. The bond energies of graphite in its potential minimum are derived from those of polynuclear benzenoїd hydrocarbons using a formula describing bond energies in terms of the charges at the bond-forming atoms. These energies plus a consideration of (i) van der Waals interactions between layers (~1.2 kcal mol−1), (ii) ZPE = 3.68, and (iii) the experimental heat content. HT − H0 = 0.25 kcal mol−1, lead to a theoretical enthalpy of atomization, ΔHa(298.15) = 174.6, which is ~2% larger than its experimental counterpart, 170.9 kcal mol−1. Exploiting the fact that the carbon atoms are electroneutral in graphite and not so in benzenoїd hydrocarbons, the results obtained for graphite support the approximate validity of bond energies deduced for polynuclear benzenoїd hydrocarbons and of the net charge, 14.8 × 10−3 e, deduced for the carbon atom of benzene.

Charge distributions and chemical effects. XXVII. Molecular energies of carbonyl compounds and ethers, a calculation involving the charges of the bond-forming atoms

1982 ◽  
Vol 60 (6) ◽  
pp. 792-800 ◽  
Author(s):  
S. Fliszár ◽  
M. T. Béraldin
Keyword(s):  
Carbonyl Compounds ◽  
Structural Changes ◽  
Minor Role ◽  
Electronic Charge ◽  
Average Deviation ◽  
Bond Forming ◽  
Chemical Effects ◽  
Coulomb Type ◽  
Individual Bond ◽  
A Minor

Energy calculations are presented for carbonyl compounds and ethers by applying the equation εij = εij0 + aijΔqi + ajiΔqj which describes individual bond contributions in terms of electronic charge increments Δq at the bond-forming atoms i and j, relative to atomic charges in selected reference bonds with energies εij0. At a molecular level, the sum ΣiΣjaijΔqi accounts for virtually the entire energy variations due to charge redistributions accompanying isodesmic structural changes. Coulomb-type interactions between nonbonded atoms play only a minor role in that respect. Using charges derived from 13C and 17O nmr shift-charge correlations, calculated and experimental energies agree within 0.16 kcal/mol (average deviation).

scholarly journals Charge distributions and chemical effects. XXIX. On the vibrational energies of chair and boat cyclohexane

1982 ◽  
Vol 60 (11) ◽  
pp. 1347-1351 ◽  
Author(s):  
J. P. Huvenne ◽  
G. Vergoten ◽  
G. Fleury ◽  
S. Odiot ◽  
S. Fliszár
Keyword(s):  
Force Field ◽  
Conformational Changes ◽  
Vibrational Energy ◽  
Zero Point ◽  
Local Symmetry ◽  
Cyclohexane Ring ◽  
Force Field Calculations ◽  
Similar Nature ◽  
Chemical Effects ◽  
Vibrational Energies

Local symmetry force field calculations are presented for the chair and boat forms of cyclohexane and the assignments of frequencies are given. The calculated zero-point and thermal vibrational energies indicate a near invariance of total vibrational energy with respect to chair–boat conformational changes of the cyclohexane ring, thus confirming results of similar nature derived from earlier theoretical thermochemical analyses.

scholarly journals Ro-vibrational energies of cesium dimer and lithium dimer with molecular attractive potential

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
C. A. Onate ◽  
T. A. Akanbi ◽  
I. B. Okon
Keyword(s):  
Thermal Properties ◽  
Attractive Potential ◽  
Average Deviation ◽  
Radial Wave ◽  
Lithium Dimer ◽  
Temperature Parameter ◽  
Vibrational Energies ◽  
Experimental Values ◽  
Uvarov Method ◽  
Potential Parameters

AbstractAn approximate solution of the Schrӧdinger equation for a molecular attractive potential was obtained using the parametric Nikiforov–Uvarov method. The energy equation and the corresponding radial wave functions were calculated. The effects of the potential parameters on the energy eigenvalues were examined. The thermal properties under the molecular attractive potential were calculated and the behaviour of the thermal properties with the maximum quantum state (λ) and the temperature parameter (β) respectively, were studied. Using the molecular spectroscopic parameters, the Rydberg–Klein–Rees (RKR) of cesium dimer and lithium dimer were both obtained and compared with the experimental values. The RKR values of both cesium dimer and lithium dimer calculated aligned with the observed values. The deviation and average deviation of the RKR for each molecule were also calculated.

Standard enthalpies of formation of N,N´-(1,3-phenylene)bis(phthalimide) and N,N´-(1,3-phenylene)bis(phthalimide-5-carboxilic acid)

2021 ◽  
pp. 178861
Author(s):  
Karina Salas-López ◽  
Miguel A. García-Castro ◽  
Patricia Amador ◽  
Ana M. Herrera-González ◽  
Alberto Galicia-Aguilar ◽  
...  
Keyword(s):  
Enthalpies Of Formation ◽  
Standard Enthalpies Of Formation
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