In:
Israel Journal of Chemistry, Wiley, Vol. 55, No. 2 ( 2015-02), p. 235-242
Abstract:
State‐of‐the‐art quantum chemical methods have been applied to describe the association of two frustrated Lewis pairs (FLPs), B(C 6 F 5 ) 3 /PR 3 ( 1 : R=2,4,6‐Me 3 C 6 H 2 ; 2 : R=CMe 3 ), with different steric demands of the base component. Interaction energies are calculated at the dispersion‐corrected DFT, MP2 (second‐order Møller‐Plesset), and DLPNO‐CCSD(T) (domain‐based local pair natural orbital‐coupled cluster, including single, double and perturbative triple excitations) levels of theory, combined with extended triple‐ or quadruple‐ζ AO (atom‐centered orbital) basis sets. Thermostatistical contributions to the free binding energy are calculated from harmonic frequencies at the efficient HF‐3c (minimal basis Hartree‐Fock with three corrections) level, while solvation effects in benzene are accounted for by the COSMO‐RS (conductor‐like screening model for realistic solvents) continuum model. Comparison with the recently measured experimental value for the free association energy of the FLP 1 reveals agreement between theory and experiment within the estimated error bars. The computed gas phase interaction energies for both FLPs are similar (about −13 kcal mol −1 ), with only small variations (about ±3 kcal mol −1 ) for various quantum chemical methods, when London dispersion interactions are accounted for properly. The association of the more “frustrated” FLP 1 is mainly driven by nondirectional dispersion forces, resulting in non‐preferential orientations, which is in agreement with experimental results. On the other hand, in FLP 2 with the “smaller” base, the boron and phosphorous atoms face each other in the favored complex structure, indicating a weak PB donor‐acceptor interaction. This conformation of 2 seems to be more suitable for small molecule (e.g., H 2 ) activations.
Type of Medium:
Online Resource
ISSN:
0021-2148
,
1869-5868
DOI:
10.1002/ijch.201400138
Language:
English
Publisher:
Wiley
Publication Date:
2015
detail.hit.zdb_id:
2066481-3
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