Multidimensional Lewis Acidity: A Consistent Data Set of Chloride, Hydride, Methide, Water and Ammonia Affinities for 183 p-Block Element Lewis Acids

Abstract

The computed fluoride ion affinity (FIA) is a widely applied descriptor to gauge Lewis acidity. Like every other single-parameter Lewis acidity scale, the FIA metric suffers from the one-dimensionality, that prohibits addressing Lewis acidity by the multidimensionality it inherently requires (i. e., reference Lewis base dependency). However, a systematic screening of computed affinities other than the FIA is much less developed. Herein, we extended our CCSD(T)/CBS benchmark of different density functionals and the DLPNO-CCSD(T) method for chloride (CIA), methide (MIA), hydride (HIA), water (WA), and ammonia (AA) affinities. The best performing methods are subsequently applied to yield nearly 800 affinities for 183 p-block element compounds of group 13-16 with an estimated accuracy of <10 kJ mol^-1 . The study's output serves as a consistent library for qualitative analyses and a training set for future statistical approaches. A first holistic correlation analysis underscores the need for a multidimensional description of Lewis acidity.

Keywords: Lewis acids; affinity scales; benchmark; computational Lewis acidity; p-block elements.

Figure 1

A–C Previously applied Lewis base affinities (XIA) and D its shortcomings considered in this work.

Figure 2

A Correlation plots comparing HIA with MIA and FIA, B CIA with MIA, FIA and AA and C WA with HIA and AA.

Figure 3

Representative comparison plots of different ligand classes: A propagation of MIA for halides, B propagation of AA for halides and C CIA for C‐substituents.

Figure 4

Correlation plots of the vacuum XIA against its respective XIA_solv, shown for water and chloride.