The potassium fluoride–boric acid system. Hydrogen bonding in KF·H<sub>3</sub>BO<sub>3</sub>

Emsley, John; Gold, Victor; Lucas, J.; Overill, Richard E.

doi:10.1039/dt9810000783

Cited by 12 publications

(18 citation statements)

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“…The geometry of the hydrogen-bond system in CuaK(H302)(SO4)2 agrees with general expectations from the literature (e.g. Olovsson & Jrnsson, 1976;Emsley, 1980;Emsley, Jones & Lucas, 1981;Chiari & Ferraris, 1982;Ferraris, Fuess & Joswig, 1986;Ardon & Bino, 1987). From X-ray investigations it is well known that among the sulfates and selenates of natrochalcite type, the hydrogen-bond lengths vary considerably: o(n)...o(n) = 2.44 to 2.61 A, o(n)...O(2)= 2.70 to 3-11/~ (Giester & Zemann, 1987Giester, 1989).…”

Section: Introduction the Title Compound Was Investigatedsupporting

confidence: 80%

Neutron diffraction study of the hydrogen-bond system in Cu2K(H3O2)(SO4)2

Chevrier¹,

Giester²,

Jarosch³

et al. 1990

Acta Crystallogr C

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Section: Introduction the Title Compound Was Investigatedsupporting

confidence: 80%

Neutron diffraction study of the hydrogen-bond system in Cu2K(H3O2)(SO4)2

Chevrier¹,

Giester²,

Jarosch³

et al. 1990

Acta Crystallogr C

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“…In model B the electric field F = 2 qe 0 / r e 2 = 2.88 × 10 5 q V cm -1 is generated by two point charges located r e = 100 Å away of the center of the hydrogen bond of the isolated complex as indicated in Figure . By comparison, an electric dipole μ at a distance r m creates a maximum electric field of F = m/4pr 3 = 2.40 × 10 8 m / r m , where r μ is in Å and μ in debye (D) . For example, a charge of q = 200 leading to an electric field of 5.76 × 10 7 V cm -1 corresponds to the electric field created by three dipoles of 5 D located at a distance of 4 Å.…”

Section: Methodsmentioning

confidence: 99%

“…In hydrogen-bonded complexes XHB between an acid HX and a base B, proton transfers can take place that are the key steps of a large number of chemical and biochemical reactions . Thus, numerous experimental and theoretical studies have been carried out to understand the properties of strong hydrogen bonds and the nature of the proton transfer in these bonds as a function of the environment. , …”

Section: Introductionmentioning

confidence: 99%

Theoretical Study of the Influence of Electric Fields on Hydrogen-Bonded Acid−Base Complexes

et al. 1997

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Matrix effects on the optimized geometries and the electronic properties of acid−base complexes XHB, with HX = HF, HCl, HBr, HCN and B = NH3, have been modeled using ab initio methods (6-31G** and 6-311++G** basis sets) in two different ways. Model A corresponds to the Onsager SCRF model, and model B corresponds to a homogeneous electric field F = 2qe 0/r e 2 = 2.88 × 105 q V/cm of varying strength generated by two distant charges +qe 0 and −qe 0 of opposite sign placed at distances of r e = 100 Å. In both models, the minima and reaction coordinate of proton transfer has been calculated. As the electric interactions are increased, both models predict an increase of the dipole moments associated with a proton shift from X to B, i.e., a conversion of the molecular to the zwitterionic complexes. Both models predicts double minima for some electric fields; in model B electric fields are found where the neutral complex is not stable, evolving to the ion pair complex. These fields can be used to characterize the acidity of the donor toward the base without the necessity of assuming a proton-transfer equilibrium. In both models a similar field-induced correlation between the two hydrogen bond distances r 1 ≡ X···H and r 2 ≡ H···B is observed for all configurations. This correlation indicates in the molecular complexes a hydrogen bond compression when the proton is shifted toward the base and in the zwitterionic complexes a widening. The minimum of the X···B distance r 1 + r 2 occurs when the proton-transfer coordinate r 1 − r 2 = r 01 − r 02, where r 01 and r 02 represent the distances X···H and H···B+ in the free donors.

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“…We label the distance between A and L as r 1 and the distance between L and B as r 2 , and neglect the bending vibration. The potential energy V ( r 1 , r 2 ) of the nuclear motion is not harmonic and contains anharmonic coupling terms . A typical two-dimensional potential energy surface is depicted schematically in Figure , where we use as coordinates the sum r 1 + r 2 and the difference r 1 − r 2 .…”

Section: General Sectionmentioning

confidence: 99%

“…The nature of low-barrier hydrogen bonds is an old problem of experimental and theoretical chemistry …”

Section: Introductionmentioning

confidence: 99%

Hydrogen/Deuterium Isotope Effects on the NMR Chemical Shifts and Geometries of Intermolecular Low-Barrier Hydrogen-Bonded Complexes

et al. 1996

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In this paper we describe H/D isotope effects on the chemical shifts of intermolecular hydrogen-bonded complexes exhibiting low barriers for proton transfer, as a function of the position of the hydrogen bond proton. For this purpose, low-temperature (100−150 K) 1H, 2H, and 15N NMR experiments were performed on solutions of various protonated and deuterated acids AL (L = H, D) and pyridine-15 N (B) dissolved in a 2:1 mixture of CDClF2/CDF3. In this temperature range, the regime of slow proton and hydrogen bond exchange is reached, leading to resolved NMR lines for each hydrogen-bonded species as well as for different isotopic modifications. The experiments reveal the formation of 1:1, 2:1, and 3:1 complexes between AH(D) and B. The heteronuclear scalar 1H−15N coupling constants between the hydrogen bond proton and the 15N nucleus of pyridine show that the proton is gradually shifted from the acid to pyridine-15 N when the proton-donating power of the acid is increased. H/D isotope effects on the chemical shifts of the hydrogen-bonded hydrons (proton and deuteron) as well as on the 15N nuclei involved in the hydrogen bonds were measured for 1:1 and 2:1 complexes. A qualitative explanation concerning the origin of these low-barrier hydrogen bond isotope effects is proposed, from which interesting information concerning the hydron and heavy atom locations in single and coupled low-barrier hydrogen bonds can be derived. Several implications concerning the role of low-barrier hydrogen bonds in enzyme reactions are discussed.

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The potassium fluoride–boric acid system. Hydrogen bonding in KF·H₃BO₃

Cited by 12 publications

References 1 publication

Neutron diffraction study of the hydrogen-bond system in Cu2K(H3O2)(SO4)2

Neutron diffraction study of the hydrogen-bond system in Cu2K(H3O2)(SO4)2

Theoretical Study of the Influence of Electric Fields on Hydrogen-Bonded Acid−Base Complexes

Hydrogen/Deuterium Isotope Effects on the NMR Chemical Shifts and Geometries of Intermolecular Low-Barrier Hydrogen-Bonded Complexes

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The potassium fluoride–boric acid system. Hydrogen bonding in KF·H3BO3

Cited by 12 publications

References 1 publication

Neutron diffraction study of the hydrogen-bond system in Cu2K(H3O2)(SO4)2

Neutron diffraction study of the hydrogen-bond system in Cu2K(H3O2)(SO4)2

Theoretical Study of the Influence of Electric Fields on Hydrogen-Bonded Acid−Base Complexes

Hydrogen/Deuterium Isotope Effects on the NMR Chemical Shifts and Geometries of Intermolecular Low-Barrier Hydrogen-Bonded Complexes

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The potassium fluoride–boric acid system. Hydrogen bonding in KF·H₃BO₃