Anharmonic frequencies and Berry pseudorotation motion in PF5

Caligiana, Andrea; Aquilanti, Vincenz̊o; Burcl, Rudolf; Handy, Nicholas C.; Tew, David P.

doi:10.1016/s0009-2614(02)02024-9

Cited by 16 publications

(11 citation statements)

References 16 publications

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“…2(a) representing the deviation of the calculated absolute entropies from experiment shows that G4 theory provides accurate predictions of the measured entropies for small rigid molecules. The results obtained for small nonrigid molecules whose conformational flexibility is caused by Berry pseudorotations [51][52][53] such as pentavalent species (PF 5 and PCl 5 ) are in agreement with experiment (Table S4). The calculated entropies are also in agreement with experiment for small ring compounds such as cyclopentane and methylcyclopentane (Table S4).…”

Section: B Enthalpy Of Formationsupporting

confidence: 84%

Large-scale calculations of gas phase thermochemistry: Enthalpy of formation, standard entropy, and heat capacity

Ghahremanpour

Maaren

Ditz

et al. 2016

The Journal of Chemical Physics

131

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Large scale quantum calculations for molar enthalpy of formation (∆ f H 0 ), standard entropy (S 0 ), and heat capacity (C V ) are presented. A large data set may help to evaluate quantum thermochemistry tools in order to uncover possible hidden shortcomings and also to find experimental data that might need to be reinvestigated, indeed we list and annotate approximately 200 problematic thermochemistry measurements. Quantum methods systematically underestimate S 0 for flexible molecules in the gas phase if only a single (minimum energy) conformation is taken into account. This problem can be tackled in principle by performing thermochemistry calculations for all stable conformations [Zheng et al., Phys. Chem. Chem. Phys. 13, 10885-10907 (2011)], but this is not practical for large molecules. We observe that the deviation of composite quantum thermochemistry recipes from experimental S 0 corresponds roughly to the Boltzmann equation (S = R ln Ω), where R is the gas constant and Ω the number of possible conformations. This allows an empirical correction of the calculated entropy for molecules with multiple conformations. With the correction we find an RMSD from experiment of ≈13 J/mol K for 1273 compounds. This paper also provides predictions of ∆ f H 0 , S 0 , and C V for well over 700 compounds for which no experimental data could be found in the literature.

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Section: B Enthalpy Of Formationsupporting

confidence: 84%

Large-scale calculations of gas phase thermochemistry: Enthalpy of formation, standard entropy, and heat capacity

Ghahremanpour

Maaren

Ditz

et al. 2016

The Journal of Chemical Physics

131

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“…Some recent applications include analysis of anharmonic frequencies [11] and pseudorotation [12] of PF 5 , the calculation of phosphorane pK a values, [13] and phosphate hydrolysis reactions. [14] Very recently, hybrid DFT has been applied to the study of biological metaphosphate, phosphate and phosphorane compounds, [15] including binding of divalent Mg 2 + ions, [16] and pseudorotation barriers of chemically modified phosphoranes.…”

Section: Introductionmentioning

confidence: 99%

Pseudorotation Barriers of Biological Oxyphosphoranes: A Challenge for Simulations of Ribozyme Catalysis

López

Faza

Lera

et al. 2005

Chemistry A European J

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Pseudorotation reactions of biologically relevant oxyphosphoranes were studied by using density functional and continuum solvation methods. A series of 16 pseudorotation reactions involving acyclic and cyclic oxyphosphoranes in neutral and monoanionic (singly deprotonated) forms were studied, in addition to pseudorotation of PF5. The effect of solvent was treated by using three different solvation models for comparison. The barriers to pseudorotation ranged from 1.5 to 8.1 kcal mol(-1) and were influenced systematically by charge state, apicophilicity of ligands, intramolecular hydrogen bonding, cyclic structure and solvation. Barriers to pseudorotation for monoanionic phosphoranes occur with the anionic oxo ligand as the pivotal atom, and are generally lower than for neutral phosphoranes. The OCH3 groups were observed to be more apicophilic than OH groups, and hence pseudorotations that involve axial OCH3/equatorial OH exchange had higher reaction and activation free energy values. Solvent generally lowered barriers relative to the gas-phase reactions. These results, together with isotope 18O exchange experiments, support the assertion that dianionic phosphoranes are not sufficiently long-lived to undergo pseudorotation. Comparison of the density functional results with those from several semiempirical quantum models highlight a challenge for new-generation hybrid quantum mechanical/molecular mechanical potentials for non-enzymatic and enzymatic phosphoryl transfer reactions: the reliable modeling of pseudorotation processes.

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“…The equilibrium geometry adopts a D 3h symmetry with two different PÀF bond lengths, one associated to axial fluorine atoms (PÀF ax bond length = 1.600 ) and the other to equatorial ones (PÀF eq bond length = 1.567 ) close to others structures obtained either experimentally (PÀF eq = 1.534 ; PÀF ax = 1.577 ) [1] or theoretically (PÀF eq and PÀF ax bond lengths ranging from 1.528 to 1.566 and from 1.563 to 1.602 , respectively). [16,17,53,54] The reaction path associated to the Berry pseudorotation mechanism proceeds through a transition state of C 4v symmetry. For this structure, four equivalent fluorine atoms exhibit a PÀF bond length of 1.591 while the remaining pivot fluorine atom, reveals a shorter PÀF bond length (1.549 ).…”

Section: Static Approachmentioning

confidence: 99%

“…The Berry pseudorotation [11,12] mechanism (Scheme 1) is commonly invoked to explain the 19 F NMR spectrum of PF 5 and much attention has been devoted to the determination of the exchange mechanism, energy barrier and exchange rate. [13][14][15][16][17] Recent developments in various computational methods for the study of nuclear magnetic resonance spectra provide new possibilities for the analysis and interpretation of experimental spectra. State-of-the-art ab initio methods nowadays allow the accurate treatment of chemical shielding and indirect spinspin coupling constants.…”

Section: Introductionmentioning

confidence: 99%

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Berry Pseudorotation Mechanism for the Interpretation of the ¹⁹F NMR Spectrum in PF₅ by Ab Initio Molecular Dynamics Simulations

et al. 2006

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For the first time, theoretical evidence that confirms the importance of the Berry pseudorotation process in the interpretation of the 19F NMR spectrum of phosphorus pentafluoride (PF5) is presented. Ab initio molecular dynamics simulations have been performed to generate a large number of configurations used for NMR parameter computations at the density functional theory level. Two different temperatures were set to highlight the effect of pseudorotation process on the NMR spectrum. Average 19F chemical shifts and spin-spin coupling constants calculated for the five fluorine atoms converge towards the NMR equivalence of the five atoms when the Berry pseudorotation mechanism is accounted for.

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Anharmonic frequencies and Berry pseudorotation motion in PF5

Cited by 16 publications

References 16 publications

Large-scale calculations of gas phase thermochemistry: Enthalpy of formation, standard entropy, and heat capacity

Large-scale calculations of gas phase thermochemistry: Enthalpy of formation, standard entropy, and heat capacity

Pseudorotation Barriers of Biological Oxyphosphoranes: A Challenge for Simulations of Ribozyme Catalysis

Berry Pseudorotation Mechanism for the Interpretation of the ¹⁹F NMR Spectrum in PF₅ by Ab Initio Molecular Dynamics Simulations

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Anharmonic frequencies and Berry pseudorotation motion in PF5

Cited by 16 publications

References 16 publications

Large-scale calculations of gas phase thermochemistry: Enthalpy of formation, standard entropy, and heat capacity

Large-scale calculations of gas phase thermochemistry: Enthalpy of formation, standard entropy, and heat capacity

Pseudorotation Barriers of Biological Oxyphosphoranes: A Challenge for Simulations of Ribozyme Catalysis

Berry Pseudorotation Mechanism for the Interpretation of the 19F NMR Spectrum in PF5 by Ab Initio Molecular Dynamics Simulations

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Berry Pseudorotation Mechanism for the Interpretation of the ¹⁹F NMR Spectrum in PF₅ by Ab Initio Molecular Dynamics Simulations