Chemistry – A European Journal
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The additional substituents arising from hypervalency present a number of complicating issues for the formation of noncovalent bonds. The XF5 molecule (X=Cl, Br, I) was allowed to form a halogen bond with NH3 as base. Hypervalent chalcogen bonding is examined by way of YF4 and YF6 (Y=S, Se, Te), and ZF5 (Z=P, As, Sb) is used to model pnicogen bonding. Pnicogen bonds are particularly strong, with interaction energies approaching 50 kcal/mol, and also involve wholesale rearrangement from trigonal bipyramidal in the monomer to square pyramidal in the complex, subject to a large deformation energy. YF4 chalcogen bonding is also strong, and like pnicogen bonding, is enhanced by a heavier central atom. XF5 halogen bond energies are roughly 9 kcal/mol, and display a unique sensitivity to the identity of the X atom. The crowded octahedral structure of YF6 permits only very weak interactions. As the F atoms of SeF6 are replaced progressively by H, a chalcogen bond appears in combination with SeH··N and NH··F H-bonds. The strongest such chalcogen bond appears in SeF3H3··NH3, with a binding energy of 7 kcal/mol, wherein the base is located in the H3 face of the Lewis acid. Results are discussed in the context of the way in which the positions and intensities of σ-holes are influenced by the locations of substituents and lone electron pairs.
Scheiner, S. I., Jia, L. (2018). Halogen, Chalcogen, and Pnicogen Bonding Involving Hypervalent Atoms. Chemistry – A European Journal, 24(32), 8167-8177. https://onlinelibrary.wiley.com/doi/abs/10.1002/chem.201800511
This is the peer reviewed version of the following article: Scheiner, S. I., Jia, L. (2018). Halogen, Chalcogen, and Pnicogen Bonding Involving Hypervalent Atoms. Chemistry – A European Journal, 24(32), 8167-8177. https://onlinelibrary.wiley.com/doi/abs/10.1002/chem.201800511, which has been published in final form at https://doi.org/10.1002/chem.201800511. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.