Microwave spectrum and structure of the 3,5-difluoropyridine⋯CO2 van der Waals complex

Dewberry, Christopher T.; Cornelius, Ryan D.; Mackenzie, Rebecca B.; Smith, Christopher J.; Dvorak, M. A.; Leopold, K. R.

doi:10.1016/j.jms.2016.08.016

Cited by 10 publications

(3 citation statements)

References 18 publications

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“…As previously discussed, for example, the diazine−water complexes have nonlinear hydrogen bonds, likely resulting from analogous secondary interactions. Moreover, the short van der Waals bond lengths and lack of internal rotation in the complexes py− CO 2 18 and 3,5-difluoropyrine−CO 2 19 have been attributed to the secondary hydrogen bonds between the CO 2 oxygens and ortho-hydrogens. In the py−HCCH complex, 13 the acetylene forms a hydrogen bond to the nitrogen, but tilts so as to bring its π electron density closer to one or the other of the orthohydrogens, producing complex internal dynamics similar to those observed here.…”

Section: ■ Discussionmentioning

confidence: 99%

Multidimensional Large Amplitude Dynamics in the Pyridine–Water Complex

et al. 2017

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Aqueous pyridine plays an important role in a variety of catalytic processes aimed at harnessing solar energy. In this work, the pyridine-water interaction is studied by microwave spectroscopy and density functional theory calculations. Water forms a hydrogen bond to the nitrogen with the oxygen tilted slightly toward either of the ortho-hydrogens of the pyridine, and a tunneling motion involving in-plane rocking of the water interconverts the resulting equivalent structures. A pair of tunneling states with severely perturbed rotational spectra is identified and their energy separation, ΔE, is inferred from the perturbations and confirmed by direct measurement. Curiously, values of ΔE are 10404.45 and 13566.94 MHz for the HO and DO complexes, respectively, revealing an inverted isotope effect upon deuteration. Small splittings in some transitions suggest an additional internal motion making this complex an interesting challenge for theoretical treatments of large amplitude motion. The results underscore the significant effect of the ortho-hydrogens on the intermolecular interaction of pyridine.

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Section: ■ Discussionmentioning

confidence: 99%

Multidimensional Large Amplitude Dynamics in the Pyridine–Water Complex

et al. 2017

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“…In these complexes, the carbon atom interacts with the nitrogen atom of NCH and NH 3 at N–C distances of 2.998 and 2.9875 Å, respectively. More recently, the structures of the pyridine:CO 2 and 3,5-difluoropyridine:CO 2 complexes have been reported. , In both cases, the complexes have planar C 2 v symmetry, with N–C distances of 2.7977 and 2.8245 Å, respectively. It is interesting that the N–C distances in the pyridine complexes are shorter than they are in the complexes with NCH and NH 3 .…”

Section: Introductionmentioning

confidence: 99%

Azines as Electron-Pair Donors to CO₂for N···C Tetrel Bonds

2017

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Ab initio MP2/aug'-cc-pVTZ calculations were performed to investigate tetrel-bonded complexes formed between CO and the aromatic bases pyridine, the diazines, triazines, tetrazines, and pentazine. Of the 23 unique equilibrium azine:CO complexes, 14 have planar structures in which a single nitrogen atom is an electron-pair donor to the carbon of the CO molecule, and 9 have perpendicular structures in which two adjacent nitrogen atoms donate electrons to CO, with bond formation occurring along an N-N bond. The binding energies of these complexes vary from 13 to 20 kJ mol and decrease as the number of nitrogen atoms in the ring increases. For a given base, planar structures have larger binding energies than perpendicular structures. The binding energies of the planar complexes also tend to increase as the distance across the tetrel bond decreases. Charge transfer in the planar pyridine:CO complex occurs from the N lone pair to a virtual nonbonding orbital of the CO carbon atom. In the remaining planar complexes, charge transfer occurs from an N lone pair to the remote in-plane π*C-O orbital. In perpendicular complexes, charge transfer occurs from an N-N bond to the adjacent π*O-C-O orbital of CO. Decreases in the bending frequency of the CO molecule and in the C chemical shielding of the C atom of CO upon complex formation are larger in planar structures compared to perpendicular structures. EOM-CCSD spin-spin coupling constants J(N-C) for complexes with planar structures are very small but still correlate with the N-C distance across the tetrel bond.

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“…The main goal here is to find a compound that is able to change the electronic distribution of CO 2 to make this very stable compound a little more reactive. In previous works, it has been shown that carbon dioxide is able to form complexes with phosphines, − sulfur dioxide, pyridine derivatives, − imidazole, − and other heterocycles. , It has also been proved that CO 2 can form adducts with carbenes − and frustrated Lewis pairs (FLPs), − some of them including silicon and germanium as Lewis acid centers. − …”

Section: Introductionmentioning

confidence: 99%

Sequestration of Carbon Dioxide with Frustrated Lewis Pairs Based on N-Heterocycles with Silane/Germane Groups

et al. 2021

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Frustrated Lewis pairs (FLPs) based on nitrogen heterocycles (pyridine, pyrazole, and imidazole) with a silane or germane group in the α-position of a nitrogen atom have been considered as potential molecules to sequestrate carbon dioxide. Three stationary points have been characterized in the reaction profile: a pre-reactive complex, an adduct minimum, and the transition state connecting them. The effect of external (solvent) or internal (hydroxyl group) electric fields in the reaction profile has been considered. In both cases, it is possible to improve the kinetics and thermodynamics of the complexation of CO 2 by the FLP and favor the formation of adducts.

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Microwave spectrum and structure of the 3,5-difluoropyridine⋯CO2 van der Waals complex

Cited by 10 publications

References 18 publications

Multidimensional Large Amplitude Dynamics in the Pyridine–Water Complex

Multidimensional Large Amplitude Dynamics in the Pyridine–Water Complex

Azines as Electron-Pair Donors to CO₂for N···C Tetrel Bonds

Sequestration of Carbon Dioxide with Frustrated Lewis Pairs Based on N-Heterocycles with Silane/Germane Groups

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Microwave spectrum and structure of the 3,5-difluoropyridine⋯CO2 van der Waals complex

Cited by 10 publications

References 18 publications

Multidimensional Large Amplitude Dynamics in the Pyridine–Water Complex

Multidimensional Large Amplitude Dynamics in the Pyridine–Water Complex

Azines as Electron-Pair Donors to CO2for N···C Tetrel Bonds

Sequestration of Carbon Dioxide with Frustrated Lewis Pairs Based on N-Heterocycles with Silane/Germane Groups

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Azines as Electron-Pair Donors to CO₂for N···C Tetrel Bonds