Vibrational frequencies and structural determination of norbornadiene

Jensen, James O.

doi:10.1016/j.theochem.2004.09.056

Cited by 5 publications

(3 citation statements)

References 47 publications

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“…Note that DGauss was itself part of Unichem, a now obsolete suite of computational quantum-chemistry programs written for (exceedingly fast) calculations on large pharmaceutical compounds, at the cost in DFT of a prune integration grid of much lower quality than with Gaussian, which by default consists of 1100 points only per atom . The BP/TZVP analysis which Mackenzie-Ross et al made of the IR and Raman vibrational spectra of norbornadiene also indicates that geometry was optimized regardless of the C 2 v symmetry point group, considering that several calculated frequencies were left without any proper symmetry label, and that most formally IR-inactive A 2 modes were ascribed some intensity, regardless of dipole selection rules in IR spectroscopy (see Table 4 in ref and compare it with the work by Jensen in ref for an assignment of the vibrational spectra of norbornadiene upon a properly optimized C 2 v geometry). A lack of control upon the symmetry characteristics of orbitals combined with errors in numerical integrations at large values of r may very well explain the too strong turn-ups and numerous oscillations that were theoretically predicted for several momentum profiles (Figure b−d) by Mackenzie-Ross et al at low electron momenta ( p < 0.25 au), apparently and strangely enough in excellent agreement with experiment. , In support of the assertion that many turn-ups at p → 0 in the theoretical momentum distributions by Mackenzie-Ross et al are numerical artifacts, note that, unlike DFT calculations, HF and ADC(3) calculations employing as here Gaussian-type AO basis sets are not subject to numerical integration problems, since all required one- and two-electron integrals are evaluated analytically.…”

Section: Resultsmentioning

confidence: 90%

Electron Momentum Spectroscopy of Norbornadiene at the Benchmark ADC(3) Level

2010

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An extensive study, throughout the valence region, of the electronic structure, ionization spectrum, and electron momentum distributions of norbornadiene is presented, on the ground of accurate calculations of valence one-electron and shake-up ionization energies and of the related Dyson orbitals, using one-particle Green's function (1p-GF) theory in conjunction with the so-called third-order algebraic diagrammatic construction scheme [ADC(3)]. Comparison is made with results obtained from standard (B3LYP) Kohn-Sham orbitals and measurements employing electron momentum spectroscopy, taking into account the contamination of inner- and outer-valence spectral bands by numerous shake-up states. Four relatively intense shake-up lines at 12.1, 16.4, 17.6, and 17.8 eV are found to yield recognizable spectral fingerprints in the EMS experiments. Valence bands at electron binding energies larger than 20 eV are subject to a complete breakdown of the orbital picture of ionization.

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Section: Resultsmentioning

confidence: 90%

Electron Momentum Spectroscopy of Norbornadiene at the Benchmark ADC(3) Level

2010

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“…As an example, dipolar coupling values, vibrational harmonic corrections obtained by using experimental frequencies, and R values, together with other useful information, are reported in Table for a single temperature corresponding to T red = 0.94. The same data for all the temperatures are reported in Tables SI-2, SI-3, and SI-4 of the Supporting Information, respectively, for the solute in EBBA, MM, and ZLI1132.…”

Section: Determination Of Ndbs Geometry and Order Parametersmentioning

confidence: 99%

Molecular Ordering and Structure of Quasi-spherical Solutes by Liquid Crystal NMR and Monte Carlo Simulations: The Case of Norbornadiene

Aroulanda

Celebre

et al. 2006

J. Phys. Chem. B

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Norbornadiene (a C2v symmetry bicyclic rigid hydrocarbon) dissolved in three different nematic mesophases has been studied by liquid crystal NMR, to contribute to a better understanding of the influence of solvents on the solute's ordering and structure. The main results achieved by this work can be summarized as follows: (i) the order parameters obtained by the analysis of the 1H NMR spectra (at different temperatures) were successfully reproduced by a recently proposed model of solute/liquid crystal interactions, by using Monte Carlo numerical simulations; (ii) the theoretical (B3LYP/6-31++G**) "equilibrium" geometry of norbornadiene, vibrationally corrected by using the force field calculated at the same level, is compatible (within, at most, a 5% error) with experimental LXNMR data. This leads to the conclusion that the structure is not significantly distorted by the tested solvents.

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“…[13][14][15][16][17][18][19][20][21][22][23] Recently, Jensen theoretically determined the structure of NBD and assigned its vibrational frequencies. 24 However, to the best of our knowledge, no study has thus far investigated the thermal dimerization reaction for NBD in the gas phase. Of these NBD dimers, like ethylene, the cyclobutane dimers should be considered as the products of the [212] cycloaddition.…”

Section: Introductionmentioning

confidence: 99%

Computational studies on the dimers and the thermal dimerization of norbornadiene

Yang

Kim

2007

J Comput Chem

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In this study, 14 norbornadiene (NBD) dimers and the thermal dimerization mechanism were studied using the hybrid density functional theory (B3LYP) and the second-order multiconfigurational perturbation theory (CASPT2). In the process of dimerization, the biradical stationary points were located using the unrestricted, broken-spin, symmetry approach. The pathways were divided into eight parts to aid the analysis of their mechanisms. Our results indicated that the process for the formation of the cage-like heptacyclo[6.6.0.0.260.3130.411059.01014] tetradecane (HCTD, D14) is highly exothermic (92.15 kcal/mol), indicating that D14 is the most stable NBD dimer. However, the formation of D14 is very difficult to achieve kinetically because of a higher barrier in the thermal dimerization. On the contrary, the formation of exo-cis-exo (D5) is kinetically favorable, but thermodynamically unfavorable at higher temperature. Therefore, the combination of both thermodynamic and kinetic factors indicated that the formation of exo-exo (D9), which resembles the product of the pseudo-Diels-Alder addition, is most likely in the NBD dimerization.

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Vibrational frequencies and structural determination of norbornadiene

Cited by 5 publications

References 47 publications

Electron Momentum Spectroscopy of Norbornadiene at the Benchmark ADC(3) Level

Electron Momentum Spectroscopy of Norbornadiene at the Benchmark ADC(3) Level

Molecular Ordering and Structure of Quasi-spherical Solutes by Liquid Crystal NMR and Monte Carlo Simulations: The Case of Norbornadiene

Computational studies on the dimers and the thermal dimerization of norbornadiene

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