Fluorine-Centered Halogen Bonding: A Factor in Recognition Phenomena and Reactivity

Metrangolo, Pierangelo; Murray, Jane S.; Pilati, Tullio; Politzer, Peter; Resnati, Giuseppe; Terraneo, Giancarlo

doi:10.1021/cg200888n

Cited by 231 publications

(198 citation statements)

References 75 publications

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“…It was in fact shown some years ago that carbon [37], nitrogen [36], oxygen [35], and fluorine [32] can all have positive σ-holes if covalently bonded to strongly electron-attracting partners. From this it follows that they can indeed form σ-hole bonds, and this has been demonstrated computationally [31,32,[35][36][37] and to some extent experimentally [41,53,54].…”

Section: The σ-Hole: Halogensmentioning

confidence: 60%

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σ-Hole Bonding: A Physical Interpretation

Politzer

Murray

Clark

2014

Topics in Current Chemistry

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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.

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Section: The σ-Hole: Halogensmentioning

confidence: 60%

“…Thus it was formerly thought that fluorine does not form halogen bonds. This has been disproved [32,53,54]. It was in fact shown some years ago that carbon [37], nitrogen [36], oxygen [35], and fluorine [32] can all have positive σ-holes if covalently bonded to strongly electron-attracting partners.…”

Section: The σ-Hole: Halogensmentioning

confidence: 99%

σ-Hole Bonding: A Physical Interpretation

Politzer

Murray

Clark

2014

Topics in Current Chemistry

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117

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“…However, the electrostatic potentials on the bond extensions are negative, although less so than on the lateral sides of the fluorines. On the other hand, fluorine does have a positive σ-hole potential when the remainder of the molecule is very strongly electron-attracting [64][65][66], e.g., in FCN. In (a), the sulfur is in the foreground, with CF2 groups behind it on both sides.…”

Section: Locations and Strengths Of Positive Potentialsmentioning

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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“…[33] Most fluorine compounds have surface electrostatic potentials that are totally negative, but in some cases, such as FOF, F-F, FCN and others, the fluorine compounds have positive regions of electrostatic potential, which allows them to interact attractively with negative sites. [34] Figure 5 showed the computed electrostatic potential of PF 6 . The result showed that some of the fluorine compounds have positive regions of electrostatic potential along the extensions of the P-F bonds.…”

Section: Resultsmentioning

confidence: 99%

Effects of Halogen Bonding in Chemical Activity of Lead(II) Electron Pair: Sonochemical Synthesis, Structural Studies, and Thermal Analysis of Novel Lead(II) Nano Coordination Polymer

Hanifehpour

Mirtamizdoust

Khomami

et al. 2015

Zeitschrift anorg allge chemie

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Abstract. The nanoflower lead(II) coordination compound {[Pb(phen)(μ-CH 3 COO)][PF 6 ]} n (1) (phen = 1,10-phenanthroline) was synthesized by a sonochemical method. The nanostructure was characterized by using scanning electron microscopy (SEM), X-ray powder diffraction, elemental analysis, and thermal analysis. The single-crystal X-ray structure shows that the overall structure of 1 is a 1D coordination polymer. Complex 1 has a bridging acetate pathway. Three halogen bonds observed in the structure and the strong halogen bonding of F-Pb causes chemical activity of the lead electron pair. This is

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Fluorine-Centered Halogen Bonding: A Factor in Recognition Phenomena and Reactivity

Cited by 231 publications

References 75 publications

σ-Hole Bonding: A Physical Interpretation

σ-Hole Bonding: A Physical Interpretation

σ-Hole Interactions: Perspectives and Misconceptions

Effects of Halogen Bonding in Chemical Activity of Lead(II) Electron Pair: Sonochemical Synthesis, Structural Studies, and Thermal Analysis of Novel Lead(II) Nano Coordination Polymer

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