On the Hydrogen Bond Breaking Ability of Fluorocarbons Containing Higher Halogens

Paolo, Thérèse Di; Sándorfy, C.

doi:10.1139/v74-540

Cited by 72 publications

(23 citation statements)

References 12 publications

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“…Analogous observations were later made for crystalline selenides 13, chlorides, bromides, and iodides 14–16. Earlier, Sandorfy and coworkers had studied σ‐hole bonding spectroscopically in organic halide solutions 17–20. Iwaoka et al have summarized and cited additional experimental work relating to selenides 21.…”

Section: Introductionmentioning

confidence: 65%

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Simultaneous σ‐hole and hydrogen bonding by sulfur‐ and selenium‐containing heterocycles

Murray

Lane

Politzer

2008

Int J of Quantum Chemistry

178

130

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When a Group V, VI, or VII atom forms a covalent bond, its bonding orbital has a deficiency of electronic charge in its outer (noninvolved) lobe. This is called a -hole. If the atom is sufficiently polarizable, the -hole may have a positive electrostatic potential which can interact with a nucleophilic site in its proximity to form a noncovalent bond. In this article, we show computationally, for a series of sulfur and selenium heterocycles, how the two -holes on each S or Se atom are affected by changes in the molecular framework and substituents. It is possible to selectively design -holes of appropriate strength and orientation for specific purposes, e.g. drug-receptor interactions or crystal engineering.

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Section: Introductionmentioning

confidence: 65%

“…σ‐Hole bonding is competitive with hydrogen bonding. This has been demonstrated both experimentally 17, 18, 34 and computationally 26. But there can also be situations in which they reinforce each other, i.e.…”

Section: Introductionmentioning

confidence: 73%

Simultaneous σ‐hole and hydrogen bonding by sulfur‐ and selenium‐containing heterocycles

Murray

Lane

Politzer

2008

Int J of Quantum Chemistry

178

130

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“…Halogen bonding involves a favorable noncovalent interaction between a covalently-bonded halogen and a negative site, such as a lone pair. Such interactions were already known to experimentalists in the 19th century [3,4], and were studied extensively in the 20th [5][6][7][8][9][10], with crystallography playing a major role [10][11][12][13]. Nevertheless the basis for halogen bonding was not really understood.…”

Section: A Brief History Of the σ-Holementioning

confidence: 99%

σ-Hole Interactions: Perspectives and Misconceptions

2017

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After a brief discussion of the σ-hole concept and the significance of molecular electrostatic potentials in noncovalent interactions, we draw attention to some common misconceptions that are encountered in that context: (1) Since the electrostatic potential reflects the contributions of both the nuclei and the electrons, it cannot be assumed that negative potentials correspond to "electron-rich" regions and positive potentials to "electron-poor" ones; (2) The electrostatic potential in a given region is determined not only by the electrons and nuclei in that region, but also by those in other portions of the molecule, especially neighboring ones; (3) A σ-hole is a region of lower electronic density on the extension of a covalent bond, not an electrostatic potential; (4) Noncovalent interactions are between positive and negative regions, which are not necessarily associated with specific atoms, so that "close contacts" between atoms do not always indicate the actual interactions.Keywords: σ-holes; noncovalent interactions; electrostatic potential; close contacts A Brief History of the σ-HoleThe σ-hole concept was introduced by Clark in the context of halogen bonding, at a conference in 2005 [1], although it did not appear in the chemical literature until 2007 [2]. Halogen bonding involves a favorable noncovalent interaction between a covalently-bonded halogen and a negative site, such as a lone pair. Such interactions were already known to experimentalists in the 19th century [3,4], and were studied extensively in the 20th [5][6][7][8][9][10], with crystallography playing a major role [10][11][12][13]. Nevertheless the basis for halogen bonding was not really understood. It was frequently rationalized as "charge transfer" from an electron "donor" (e.g., the lone pair) to an "acceptor" (the halogen), invoking the valence bond formalism of Mulliken [14] (which was later put in molecular orbital terms by Flurry [15,16]).However, the halogen is the most electronegative atom in each row of the periodic table, and a singly-bonded halogen atom is generally viewed as being negative in character. So why should it interact attractively with a donor of electronic charge? It was in fact pointed out long ago [7,17] that Mulliken's charge-transfer formalism was not intended to be an elucidation of the bonding in a ground-state noncovalent complex; it was purely a mathematical modeling of the transition of the ground-state complex to a low-lying excited state. The existence of halogen bonding was thus viewed by many as an enigma.The key to resolving the enigma was the molecular electrostatic potential. This is the potential V(r) that is created at any point r in the space of a molecule by its nuclei and electrons, given rigorously by Equation (1):Z A is the charge on nucleus A, located at R A , and ρ(r) is the molecule's electronic density. Regions in which V(r) is positive, indicating the dominance of the nuclear contribution, are attractive to

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“…For example, it was shown that infra-red peaks due to solute-solvent hydrogen bonds are considerably diminished by the addition of a co-solute that can -hole bond with the solvent [9,10]. In another demonstration, compounds that are known to co-crystallize with both hydrogen bond donors and halogen bond donors were found, when simultaneously dissolved with both, to form co-crystals only with the latter [26].…”

Section: -Hole Bonding and Hydrogen Bondingmentioning

confidence: 99%

σ‐Hole bonding and hydrogen bonding: Competitive interactions

Politzer

Murray

Lane

2007

Int J of Quantum Chemistry

304

178

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ABSTRACT:In certain molecular environments, a covalently-bonded atom from Groups V-VII may have a region of significantly-positive electrostatic potential on its outer side, along the extension of a covalent bond. This is due to the electron-deficient outer lobe of a half-filled p bonding orbital, which is called a "-hole." -Hole bonding is the resulting highly directional noncovalent interaction that may occur with a nucleophile, e.g., a lone pair of a Lewis base. In this article, we compare the computed interaction energies and vibrational frequency shifts associated with the formation of a series of -hole-bonded and hydrogen-bonded complexes. When the molecular environments of the atoms of Groups V-VII and the hydrogen are similar, then the hydrogen bond is usually the stronger one, although there are exceptions, as in the case of bromine. Overall, however, -hole bonding can certainly be competitive with hydrogen bonding.

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On the Hydrogen Bond Breaking Ability of Fluorocarbons Containing Higher Halogens

Cited by 72 publications

References 12 publications

Simultaneous σ‐hole and hydrogen bonding by sulfur‐ and selenium‐containing heterocycles

Simultaneous σ‐hole and hydrogen bonding by sulfur‐ and selenium‐containing heterocycles

σ-Hole Interactions: Perspectives and Misconceptions

σ‐Hole bonding and hydrogen bonding: Competitive interactions

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