The role of coupling in intramolecular proton transfer reactions. The hydrogen oxalate anion as an example

Bosch, Enric; Moreno, Miquel; Lluch, José M.

doi:10.1139/v92-017

Cited by 10 publications

(12 citation statements)

References 23 publications

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“…Though the coordinated water molecules hydrogen bond with oxalate molecules (Fig. S15), II is not conductive, meaning that the protons do not transport through oxalate ions (e.g., intramolecular proton transport) 40 as shown in Fig. S16 and need additional water molecules as carriers.…”

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confidence: 99%

Insulator-to-Proton-Conductor Transition in a Dense Metal–Organic Framework

et al. 2015

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Metal-organic frameworks (MOFs) are prone to exhibit phase transitions under stimuli such as changes in pressure, temperature, or gas sorption because of their flexible and responsive structures. Here we report that a dense MOF, ((CH3)2NH2)2[Li2Zr(C2O4)4], exhibits an abrupt increase in proton conductivity from <10(-9) to 3.9 × 10(-5) S/cm at 17 °C (activation energy, 0.64 eV) upon exposure to humidity. The conductivities were determined using single crystals, and the structures were analyzed by X-ray diffraction and X-ray pair distribution function analysis. The initial anhydrous structure transforms to another dense structure via topotactic hydration (H2O/Zr = 0.5), wherein one-fourth of the Li ions are irreversibly rearranged and coordinated by water molecules. This structure further transforms into a third crystalline structure by water uptake (H2O/Zr = 4.0). The abrupt increase in conductivity is reversible and is associated with the latter reversible structure transformation. The H2O molecules coordinated to Li ions, which are formed in the first step of the transformation, are considered to be the proton source, and the absorbed water molecules, which are formed in the second step, are considered to be proton carriers.

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confidence: 99%

Insulator-to-Proton-Conductor Transition in a Dense Metal–Organic Framework

et al. 2015

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“…6. : ~ The additional entry corresponds to the second position of the disordered part of the PEN molecules (see, text (3) ~f The numbering of the atoms correspond to that used in Table 4 & Frisch, 1992;Latajka & Scheiner, 1992;Bosch, Moreno & Lluch, 1992). This molecule belongs to the simplest fl-diketones.…”

Section: Results Of Calculationsmentioning

confidence: 99%

Resonance assisted hydrogen bonds between oxime and carboxyl group. The comparison of tetrameric structures of 4-methyl-2-oxopentanoic acid oxime and levulinic acid oxime

Maurin¹,

Winnicka-Maurin²,

Leś³

1993

Acta Cryst Sect A

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Crystal structures of oximes of two aliphatic keto-carboxylic acids, 4-methyl-2-oxopentanoic acid oxime [(PEN) 4-methyl-2-(hydroxylimino)pentanoic acid] and levulinic acid oxime [(LEV) 4-(hydroxylimino)pentanoic acid], were determined by X-ray structural methods. The molecular structures of monomers interacting via hydrogen-bond networks were analysed with the use of theoretical ab initio self-consistent field (SCF) calculations on model systems. The results of present crystallographic and theoretical studies show that a different structure of PEN and LEV crystals originates mostly from electron charge distribution, depending on the relative position of the oxime and carboxyl moieties. The observed N--O and N--C bond lengths and OmH • • .N and O--H. • .O hydrogen-bond contacts in PEN crystals are affected by the rr-electron resonance of the oxime and carboxyl moieties in a way similar to that found in /~diketones.

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“…As mentioned previously, the oxalate anion can be regarded as a complex of a proton (H + ) and an oxalate dianion (C 2 O 4 2− ) and has been previously studied experimentally and theoretically due to its unique structure [7][8][9][10][11][12][13][14][15]. The oxalate anion has two stable minima on the potential energy surface.…”

Section: Introductionmentioning

confidence: 99%

“…The oxalate anion is a molecular system that contains CO 2 molecular units with various charge states, which are important for understanding the activation of carbon dioxide [ 6 ]. As mentioned previously, the oxalate anion can be regarded as a complex of a proton (H + ) and an oxalate dianion (C 2 O 4 2 − ) and has been previously studied experimentally and theoretically due to its unique structure [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. The oxalate anion has two stable minima on the potential energy surface.…”

Section: Introductionmentioning

confidence: 99%

“…The oxalate anion has two stable minima on the potential energy surface. One is a closed-form, in which the proton is asymmetrically bound between the two oxygen atoms, forming a planar structure with a five-membered cyclic ionic hydrogen bond, and this structure has an ideal geometry for studying proton-transfer dynamics between the two oxygen atoms [ 7 , 8 , 9 , 10 , 11 , 13 ]. The other is an open-form, in which the proton in the OH bond points out of the molecular framework with an O-C-C-O angle of 90°.…”

Section: Introductionmentioning

confidence: 99%

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On-the-Fly Ring-Polymer Molecular Dynamics Calculations of the Dissociative Photodetachment Process of the Oxalate Anion

et al. 2021

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The dissociative photodetachment dynamics of the oxalate anion, C2O4H− + hν → CO2 + HOCO + e−, were theoretically studied using the on-the-fly path-integral and ring-polymer molecular dynamics methods, which can account for nuclear quantum effects at the density-functional theory level in order to compare with the recent experimental study using photoelectron–photofragment coincidence spectroscopy. To reduce computational time, the force acting on each bead of ring-polymer was approximately calculated from the first and second derivatives of the potential energy at the centroid position of the nuclei beads. We find that the calculated photoelectron spectrum qualitatively reproduces the experimental spectrum and that nuclear quantum effects are playing a role in determining spectral widths. The calculated coincidence spectrum is found to reasonably reproduce the experimental spectrum, indicating that a relatively large energy is partitioned into the relative kinetic energy between the CO2 and HOCO fragments. This is because photodetachment of the parent anion leads to Franck–Condon transition to the repulsive region of the neutral potential energy surface. We also find that the dissociation dynamics are slightly different between the two isomers of the C2O4H− anion with closed- and open-form structures.

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The role of coupling in intramolecular proton transfer reactions. The hydrogen oxalate anion as an example

Cited by 10 publications

References 23 publications

Insulator-to-Proton-Conductor Transition in a Dense Metal–Organic Framework

Insulator-to-Proton-Conductor Transition in a Dense Metal–Organic Framework

Resonance assisted hydrogen bonds between oxime and carboxyl group. The comparison of tetrameric structures of 4-methyl-2-oxopentanoic acid oxime and levulinic acid oxime

On-the-Fly Ring-Polymer Molecular Dynamics Calculations of the Dissociative Photodetachment Process of the Oxalate Anion

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