Accurate,
Precise, and Efficient Theoretical Methods To Calculate Anion−π
Interaction Energies in Model Structures
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Abstract
A correct
description of the anion−π interaction is essential for
the design of selective anion receptors and channels and important
for advances in the field of supramolecular chemistry. However, it
is challenging to do accurate, precise, and efficient calculations
of this interaction, which are lacking in the literature. In this
article, by testing sets of 20 binary anion−π complexes
of fluoride, chloride, bromide, nitrate, or carbonate ions with hexafluorobenzene,
1,3,5-trifluorobenzene, 2,4,6-trifluoro-1,3,5-triazine, or 1,3,5-triazine
and 30 ternary π–anion−π′ sandwich
complexes composed from the same monomers, we suggest domain-based
local-pair natural orbital coupled cluster energies extrapolated to
the complete basis-set limit as reference values. We give a detailed
explanation of the origin of anion−π interactions, using
the permanent quadrupole moments, static dipole polarizabilities,
and electrostatic potential maps. We use symmetry-adapted perturbation
theory (SAPT) to calculate the components of the anion−π
interaction energies. We examine the performance of the direct random
phase approximation (dRPA), the second-order screened exchange (SOSEX),
local-pair natural-orbital (LPNO) coupled electron pair approximation
(CEPA), and several dispersion-corrected density functionals (including
generalized gradient approximation (GGA), meta-GGA, and double hybrid
density functional). The LPNO-CEPA/1 results show the best agreement
with the reference results. The dRPA method is only slightly less
accurate and precise than the LPNO-CEPA/1, but it is considerably
more efficient (6–17 times faster) for the binary complexes
studied in this paper. For 30 ternary π–anion−π′
sandwich complexes, we give dRPA interaction energies as reference
values. The double hybrid functionals are much more efficient but
less accurate and precise than dRPA. The dispersion-corrected double
hybrid PWPB95–D3(BJ) and B2PLYP–D3(BJ) functionals perform
better than the GGA and meta-GGA functionals for the present test
set