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Abstract The ability of an anion to serve as electron‐accepting Lewis acid in a noncovalent bond is assessed via DFT calculations. NH3is taken as the common base, and is paired with a host of ACln−anions, with central atom A=Ca, Sr, Mg, Te, Sb, Hg, Zn, Ag, Ga, Ti, Sn, I, and B. Each anion reacts through its σ or π‐hole although the electrostatic potential of this hole is quite negative in most cases. Despite the contact between this negative hole and the negative region of the approaching nucleophile, the electrostatic component of the interaction energy of each bond is highly favorable, and accounts for more than half of the total attractive energy. The double negative charge of dianions precludes a stable complex with NH3.
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Halogen Bonding to the π‐Systems of Polycyclic Aromatics
Abstract The propensity of the π‐electron system lying above a polycyclic aromatic system to engage in a halogen bond is examined by DFT calculations. Prototype Lewis acid CF3I is placed above the planes of benzene, naphthalene, anthracene, phenanthrene, naphthacene, chrysene, triphenyl, pyrene, and coronene. The I atom positions itself some 3.3–3.4 Å above the polycyclic plane, and the associated interaction energy is about 4 kcal/mol. This quantity is a little smaller for benzene, but is roughly equal for the larger polycyclics. The energy only oscillates a little as the Lewis acid slides across the face of the polycyclic, preferring regions of higher π‐electron density over minima of the electrostatic potential. The binding is dominated by dispersion which contributes half of the total interaction energy.
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- Award ID(s):
- 1954310
- PAR ID:
- 10642662
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemPhysChem
- Volume:
- 25
- Issue:
- 18
- ISSN:
- 1439-4235
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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