Factors affecting the strengths of σ-hole electrostatic potentials

Murray, Jane S.; Macaveiu, Laura; Politzer, Peter

doi:10.1016/j.jocs.2014.01.002

Cited by 82 publications

(71 citation statements)

References 92 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Fluorine is more electron-attracting than bromine, but the VS,max due to the F-As and Br-As bonds are the same, 42 kcal/mol. Thus, while there has been some success in relating relative VS,max values to electronegativities and polarizabilities [61,68], we nevertheless echo our earlier statement [61]: "…. in the final analysis the safest approach is to simply compute them.…”

supporting

confidence: 73%

“…For singly-bonded halogens, the magnitudes of the potentials related to their σ-holes tend qualitatively to become more positive as the remainder of the molecule is more electron-attracting. Thus they depend upon the relative electronegativities and polarizabilities of the halogen and the molecular residue [47,60,61]. This is why crystal engineering through halogen bonding has so frequently involved iodides [62,63]; iodine is the least electronegative and most polarizable halogen, and thus its σ-hole potentials are usually more positive than those of the other halogens.…”

Section: Locations and Strengths Of Positive Potentialsmentioning

confidence: 99%

See 1 more Smart Citation

σ-Hole Interactions: Perspectives and Misconceptions

2017

Self Cite

View full text Add to dashboard Cite

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

show abstract

supporting

confidence: 73%

Section: Locations and Strengths Of Positive Potentialsmentioning

confidence: 99%

σ-Hole Interactions: Perspectives and Misconceptions

2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…In general, the more polarizable the halogen atom and the more electronattracting the remainder of the molecule, the more positive is the halogen σ-hole [27][28][29][30]. This is illustrated by the computed V S,max in Table 1.…”

Section: The σ-Hole: Halogensmentioning

confidence: 93%

“…4, 5, and 6. For a more general discussion of factors affecting σ-hole potentials, see Murray et al [30]. Phosphorus is in the middle facing the viewer, the cyano group is on the left, the methyl group is at the top right, and fluorine is at the bottom right.…”

Section: The σ-Hole: Halogensmentioning

confidence: 99%

σ-Hole Bonding: A Physical Interpretation

Politzer

Murray

Clark

2014

Topics in Current Chemistry

Self Cite

150

117

View full text Add to dashboard Cite

The anisotropic electronic densities of covalently-bonded Group IV-VII atoms frequently give rise to regions of positive electrostatic potential on the extensions of covalent bonds to these atoms. Through such positive "σ-holes," the atoms can interact attractively and highly directionally with negative sites such as the lone pairs of Lewis bases, anions, π electrons, etc. In the case of Group VII this is called "halogen bonding." Hydrogen bonding can be viewed as a less directional subset of σ-hole interactions. Since positive σ-holes often exist in conjunction with regions of negative potential, the atoms can also interact favorably with positive sites. In accordance with the Hellmann-Feynman theorem, all of these interactions are purely Coulombic in nature (which encompasses polarization and dispersion). The strength of σ-hole bonding increases with the magnitudes of the potentials of the positive σ-hole and the negative site; their polarizabilities must sometimes also be taken explicitly into account.

show abstract

“…This is very surprising since covalently bonded halogen atoms are usually negatively charged and thus would not be expected to interact attractively with other negative site. However, a detailed analysis of the electrostatic potential around the halogen atoms indicates the existence of an electron-deficient region, called as ''r-hole'' [10][11][12][13][14][15][16][17][18][19][20], directed toward the electron donor. The presence or absence and the magnitude of a r-hole depend upon several factors, including the polarizability and electronegativity of the halogen atom and the electron-withdrawing ability of the remainder of the molecule.…”

Section: Introductionmentioning

confidence: 99%

Competition between chalcogen bond and halogen bond interactions in YOX4:NH3 (Y = S, Se; X = F, Cl, Br) complexes: An ab initio investigation

2016

View full text Add to dashboard Cite

Using ab initio calculations, the geometries, interaction energies and bonding properties of chalcogen bond and halogen bond interactions between YOX 4 (Y = S, Se; X = F, Cl, Br) and NH 3 molecules are studied. These binary complexes are formed through the interaction of a positive electrostatic potential region (r-hole) on the YOX 4 with the negative region in the NH 3 . The ab initio calculations are carried out at the MP2/augcc-pVTZ level, through analysis of molecular electrostatic potentials, quantum theory of atoms in molecules and natural bond orbital methods. Our results indicate that even though the chalcogen and halogen bonds are mainly dominated by electrostatic effects, but the polarization and dispersion effects also make important contributions to the total interaction energy of these complexes. The examination of interaction energies suggests that the chalcogen bond is always favored over the halogen bond for all of the binary YOX 4 :NH 3 complexes.

show abstract

Factors affecting the strengths of σ-hole electrostatic potentials

Cited by 82 publications

References 92 publications

σ-Hole Interactions: Perspectives and Misconceptions

σ-Hole Interactions: Perspectives and Misconceptions

σ-Hole Bonding: A Physical Interpretation

Competition between chalcogen bond and halogen bond interactions in YOX4:NH3 (Y = S, Se; X = F, Cl, Br) complexes: An ab initio investigation

Contact Info

Product

Resources

About