DFT and IsoStar Analyses to Assess the Utility of σ‐ and π‐Hole Interactions for Crystal Engineering

Mooibroek, Tiddo J.

doi:10.1002/cphc.202000927

Cited by 9 publications

(11 citation statements)

References 172 publications

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“…R F (F_C 6 F 5 , H_X) is unexpectedly low. Possibly this is because the −C 6 F 5 group has distinct interaction preferences (e.g., stacking with electron-rich π-systems, forming anion−π or lone pair−π interactions ,, ) that may override other factors in determining packing arrangements. The R F value for F_ali is higher than those of the −CF 3 atom types.…”

Section: Results and Discussionmentioning

confidence: 99%

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Intermolecular Interactions of Organic Fluorine Seen in Perspective

Cole

Taylor

2022

Crystal Growth & Design

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In this study, we have assessed the influence that different types of fluorine interactions have on how molecules pack. This was done by taking each type of interaction in turn and establishing the ratio of its frequency of occurrence in organic crystal structures to the frequency expected if packing were random. The results allow us to see fluorine interactions in perspective: which are the most influential and which the least. Only a few of the interactions occur more often than would be expected by chance, and those few are not the strongest interactions that fluorine can make. The intramolecular environment of fluorine can strongly influence the interactions it makes, despite the general view that this element has low polarizability. The amphiphilic nature of the trifluoromethyl group is clearly seen, but F•••F interactions between −CF 3 fluorine atoms occur appreciably more often than expected by chance only in centrosymmetric structures. Many other insights were obtained in this objective analysis of the interactions of organic fluorine.

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Section: Results and Discussionmentioning

confidence: 99%

“…Other interesting questions are the extent to which fluorine accepts halogen bonds from the heavier halogens; whether tetrel bonding − between fluorine and tetrahedral carbon atoms is of any importance; and the propensity of fluorine to interact with the electropositive π-face of carbonyl carbon or nitro nitrogen. − …”

Section: Introductionmentioning

confidence: 99%

Intermolecular Interactions of Organic Fluorine Seen in Perspective

Cole

Taylor

2022

Crystal Growth & Design

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“…Charge-assisted HBs, where X–H is cationic and/or Y is anionic, are particularly strong. , It is thus no surprise that the interaction energies of simple hydrogen bonding interactions can vary greatly. The interaction energy between the very weakly polarized C–H of methane and the π-bond of, e.g., ethylene is approximately −0.7 kcal·mol –1 . ,, Such weak interactions represent the under-boundary of what can be interpreted as a hydrogen bonding interaction and are typically driven by dispersion. ,− While an energy of −0.7 kcal·mol –1 is very small, it must be noted that a difference of 0.5 kcal·mol –1 in a transition state has been reported to impact selectivity in catalysis . HBs with more polarized hydrogens, such as in amines, amides, and alcohols, are much stronger and more common.…”

Section: Fundamentals Of Hydrogen Bondingmentioning

confidence: 99%

Transition Metal Catalysis Controlled by Hydrogen Bonding in the Second Coordination Sphere

et al. 2022

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Transition metal catalysis is of utmost importance for the development of sustainable processes in academia and industry. The activity and selectivity of metal complexes are typically the result of the interplay between ligand and metal properties. As the ligand can be chemically altered, a large research focus has been on ligand development. More recently, it has been recognized that further control over activity and selectivity can be achieved by using the “second coordination sphere”, which can be seen as the region beyond the direct coordination sphere of the metal center. Hydrogen bonds appear to be very useful interactions in this context as they typically have sufficient strength and directionality to exert control of the second coordination sphere, yet hydrogen bonds are typically very dynamic, allowing fast turnover. In this review we have highlighted several key features of hydrogen bonding interactions and have summarized the use of hydrogen bonding to program the second coordination sphere. Such control can be achieved by bridging two ligands that are coordinated to a metal center to effectively lead to supramolecular bidentate ligands. In addition, hydrogen bonding can be used to preorganize a substrate that is coordinated to the metal center. Both strategies lead to catalysts with superior properties in a variety of metal catalyzed transformations, including (asymmetric) hydrogenation, hydroformylation, C–H activation, oxidation, radical-type transformations, and photochemical reactions.

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“…Selective binding of anions is one example. Whereas some of the earlier ditopic receptors made use of H-bonds, more recent work has taken advantage of various sorts of σ-hole bonds to improve on the binding strength and selectivity. − The σ-hole bonds have grown in terms of their impact on synthesis and catalysis, − crystal and polymer design, − ionic liquids, biological activity, − chromatography, and electronic materials …”

Section: Introductionmentioning

confidence: 99%

Dissection of the Origin of π-Holes and the Noncovalent Bonds in Which They Engage

Scheiner

2021

J. Phys. Chem. A

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Accompanying the rapidly growing list of σ-hole bonds has come the acknowledgment of parallel sorts of noncovalent bonds which owe their stability in large part to a deficiency of electron density in the area above the molecular plane, known as a π-hole. The origins of these π-holes are probed for a wide series of molecules, comprising halogen, chalcogen, pnicogen, tetrel, aerogen, and spodium bonds. Much like in the case of their σ-hole counterparts, formation of the internal covalent π-bond in the Lewis acid molecule pulls density toward the bond midpoint and away from its extremities. This depletion of density above the central atom is amplified by an electron-withdrawing substituent. At the same time, the amplitude of the π*-orbital is enhanced in the region of the density-depleted π-hole, facilitating a better overlap with the nucleophile’s lone pair orbital and a stabilizing n → π* charge transfer. The presence of lone pairs on the central atom acts to attenuate the π-hole and shift its position somewhat, resulting in an overall weakening of the π-hole bond. There is a tendency for π-hole bonds to include a higher fraction of induction energy than σ-bonds with proportionately smaller electrostatic and dispersion components, but this distinction is less a product of the σ- or π-character and more a function of the overall bond strength.

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DFT and IsoStar Analyses to Assess the Utility of σ‐ and π‐Hole Interactions for Crystal Engineering

Cited by 9 publications

References 172 publications

Intermolecular Interactions of Organic Fluorine Seen in Perspective

Intermolecular Interactions of Organic Fluorine Seen in Perspective

Transition Metal Catalysis Controlled by Hydrogen Bonding in the Second Coordination Sphere

Dissection of the Origin of π-Holes and the Noncovalent Bonds in Which They Engage

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