Analyzing Fluoride Binding by Group 15 Lewis Acids: Pnictogen Bonding in the Pentavalent State

We report the results of a computational investigationinto fluoridebinding by a series of pentavalent pnictogen Lewis acids: pnictogenpentahalides (PnX(5)), tetraphenyl pnictogeniums (PnPh(4) (+)), and triphenyl pnictogen tetrachlorocatecholates(PnPh(3)Cat). Activation strain and energy decompositionanalyses of the Lewis adducts not only clearly delineate the electrostaticand orbital contributions to these acid-base interactions butalso highlight the importance of Pauli repulsion and molecular flexibilityin determining relative Lewis acidity among the pnictogens. Among pentavalent pnictogen Lewis acids,antimony-basedspecies stand out as the strongest fluoride binders. Computationalactivation strain and energy decomposition analyses highlight theimportance of Pauli repulsion and molecular flexibility in determiningthis relative Lewis acidity.

Automated summary

We present the findings of a computational study on the binding of fluoride by various pentavalent pnictogen Lewis acids. Through activation strain and energy decomposition analyses, we identified the electrostatic and orbital contributions to these acid-base interactions, as well as the significance of Pauli repulsion and molecular flexibility in determining relative Lewis acidity among the pnictogens. Our results highlight antimony-based species as the strongest fluoride binders, and emphasize the importance of Pauli repulsion and molecular flexibility in determining this relative Lewis acidity.