Chloranilic acid: a redetermination at 100 K

Dutkiewicz, Grzegorz; Yathirajan, H. S.; Al-Arique, Q. N. M. Hakim; Narayana, B.; Kubicki, Maciej

doi:10.1107/s1600536810003387

Cited by 7 publications

(10 citation statements)

References 13 publications

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“…In these molecular complexes, chloranilic acid can exist as the neutral molecule, a singly deprotonated anion (HCA − ) and a doubly deprotonated dianion ( In the anions derived from H 2 CA, a charge delocalization occurs and this clearly has an influence on the interatomic distances. The bond lengths in the chloranilate mono-and dianions were compared with those in the neutral molecule 43 (Tables S8-S10 † (5) Å. This is consistent with that found in the related bromanilic acid complexes, 14 and due to the inversion center in the doubly deprotonated anion [CA 2− ], this bond length effect is symmetrical on both sides of the molecule.…”

Section: Molecular Structuresupporting

confidence: 78%

High resolution X-ray and neutron diffraction studies on molecular complexes of chloranilic acid and lutidines

et al. 2016

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A total of 18 molecular complexes of chloranilic acid (H 2 CA) and various isomeric dimethylpyridine (lutidine) bases (B) in a 1 : 1 and 1 : 2 stoichiometric ratio have been prepared and characterised structurally; 10 of the structural determinations used high resolution crystallography. Since proton transfer between the acid and base occurs in all the crystalline forms, they are most appropriately described as salts between the lutidinium cations [BH + ] and the chloranilate mono-and dianions [HCA − ] and [CA 2− ]. The formation of bifurcated or non-bifurcated charge-assisted hydrogen bonds is described and the influence of the different functional groups on symmetrical or asymmetrical bifurcated hydrogen bond formation are investigated. Previously unreported salts of the composition [BH + ]ĳHCA − ] with 2,3-and 3,5-lutidine, and [BH + ] 2 [CA 2− ] with 2,3-, 2,4-, 2,5-, 2 ,6-and 3,4-lutidine are reported, as well as di-and trihydrate forms of the latter salt type with 2,4-and 3,4-lutidine respectively. For the 2,4-and 3,5-lutidines only, molecular complexes containing co-existing charged and neutral chloranilic acid molecules are also observed. The charge delocalisation in the chloranilate anions, which has an influence on the hydrogen bond distances, is confirmed by the deformation density plots, atomic net charge calculations and the density at the bond critical points. The QTAIM molecular graphs, which show the presence of bifurcated or non-bifurcated hydrogen bonds, are highly dependent on the exact refinement model. Lattice energy calculations based on the experimental charge densities also show a high dependence on the refinement strategy, while theoretical lattice energy calculations using different approaches provide no consistency in the rank order stabilities. We conclude that neither experimental nor theoretical approaches are currently sufficiently accurate to determine a definitive stability order for such isomeric complexes. CrystEngCommThis journal is

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Section: Molecular Structuresupporting

confidence: 78%

High resolution X-ray and neutron diffraction studies on molecular complexes of chloranilic acid and lutidines

et al. 2016

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“…The acid molecules of the dimer are linked by two symmetry equivalent O–H···O HBs, forming an R 2 2 (10) hydrogen-bonded ring in a similar manner to that found in other molecular complexes containing singly deprotonated CLA – molecules . These O–H···O HBs are only moderate in strength, with an O···O distance of 2.681(5) Å; this is shorter than the HB observed in the neutral, pure CLA structure where the O···O distance of the HB is 2.752 Å . Also compared with pure CLA, where the electron density is distributed equally on each side of the molecule as it is located on an inversion center, the electron density on the CLA – molecule in 4 is skewed toward the side of the molecule nearer the DMANH + moiety and away from the side of the molecule involved in the HB of the dimer; this can be inferred by the C–O bond distances which are shortest on the side pointing toward DMANH + (1.213(2) and 1.236(2) Å) and longer on the side involved in the dimer HB (1.323(2) Å for the protonated oxygen and 1.252(2) Å for the other oxygen).…”

Section: Results and Discussionsupporting

confidence: 52%

The Effect of Local Crystalline Environment on Hydrogen Atom Behavior in Molecular Complexes of a Proton Sponge

Jones

Kállay

Lloyd

et al. 2016

Crystal Growth & Design

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Proton behavior within the hydrogen bond (HB) networks of five molecular complexes of the proton sponge DMAN and different organic acids is investigated by single crystal neutron diffraction. The complexes form with either 2:1 (acid:DMAN) or 1:1 stoichiometric ratios and contain common structural motifs. All show proton transfer from an acid to DMAN forming a DMANH + moiety and hydrogen bonded acid dimers; complexes with halobenzoic acids have acid molecules linked by short, strong, charge-assisted HBs, while all complexes contain a short, strong, intramolecular N-H•••N HB in DMANH +. The hydrogen atom behavior within the short, strong HBs, accurately described from the neutron data, is rationalized in terms of weak interactions in the local crystal environment, with the position of the proton within both sets of short, strong HBs affected by a combination of the weak interactions in the vicinity of the HBs. A correlation is also found between the thermal motion of the bound proton in the N-H•••N HB of DMANH + and nearby oxygen atoms when they are sufficiently close to one another. This work shows that all interactions in the local environment combine to determine the behavior of protons within short, strong HBs and that by taking these interactions into account further control over the crystal structure and properties may be achievable.

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“…5. The NQR and structural data are taken from the following references: quinolinic acid [9,17], maleic acid [8,18], squaric acid [6,4], acetic acid [8,19], formic acid [8,20], 2-nitrobenzoic acid [10,21], acrylic acid [8,22], a-and b-oxalic acid [8,23,24], fumaric acid [8,25] and chloranilic acid [7,26].…”

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confidence: 99%

¹⁷O NQR and ¹³C NMR study of hydrogen‐bonded organic ferroelectric croconic acid

Seliger

Plavec

Šket

et al. 2011

Physica Status Solidi (b)

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The 1H17O nuclear quadrupole double resonance spectrum and the 13C CP/MAS NMR spectrum of polycrystalline croconic acid, H2C5O5, have been studied at room temperature. Croconic acid has been recently shown to have the highest switchable spontaneous polarization of all organic ferroelectrics and stays polarized up to the decomposition point at around 450 K. Both the 13C NMR and the 17O nuclear quadrupole resonance (NQR) spectra show that there are five crystallorgaphically non‐equivalent carbon and oxygen positions for a given molecule and that therefore the two OH…O bonds are non‐equivalent. From the dipolar structure of the 17O quadrupole resonance spectra the OH distance is determined as being 0.099 ± 0.001 nm in both hydrogen bonds. The large 17O quadrupole coupling constant at the COH as well as at the CO…H oxygen position and the short OH distance demonstrate that the OH…O hydrogen bonds are strongly asymmetric. A correlation of the 17OH…O and OH…17O quadrupole coupling constants versus the O…O distance has been observed in several organic acids. The data for croconic acid significantly deviate from this correlation, what may be the result of the strong long range ferroelectric ordering which influences the electron distribution in the hydrogen bonds.

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Chloranilic acid: a redetermination at 100 K

Cited by 7 publications

References 13 publications

High resolution X-ray and neutron diffraction studies on molecular complexes of chloranilic acid and lutidines

High resolution X-ray and neutron diffraction studies on molecular complexes of chloranilic acid and lutidines

The Effect of Local Crystalline Environment on Hydrogen Atom Behavior in Molecular Complexes of a Proton Sponge

¹⁷O NQR and ¹³C NMR study of hydrogen‐bonded organic ferroelectric croconic acid

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Chloranilic acid: a redetermination at 100 K

Cited by 7 publications

References 13 publications

High resolution X-ray and neutron diffraction studies on molecular complexes of chloranilic acid and lutidines

High resolution X-ray and neutron diffraction studies on molecular complexes of chloranilic acid and lutidines

The Effect of Local Crystalline Environment on Hydrogen Atom Behavior in Molecular Complexes of a Proton Sponge

17O NQR and 13C NMR study of hydrogen‐bonded organic ferroelectric croconic acid

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¹⁷O NQR and ¹³C NMR study of hydrogen‐bonded organic ferroelectric croconic acid