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Modulation of Stacking Interactions by Transition‐Metal Coordination: Ab Initio Benchmark Studies
Author(s) -
Mutter Shaun T.,
Platts James A.
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200902813
Subject(s) - stacking , ab initio , chemistry , computational chemistry , basis set , extrapolation , aromaticity , atomic orbital , ab initio quantum chemistry methods , density functional theory , crystallography , molecule , physics , quantum mechanics , mathematics , organic chemistry , electron , mathematical analysis
A series of ab initio calculations are used to determine the CH⋅⋅⋅π and π⋅⋅⋅π‐stacking interactions of aromatic rings coordinated to transition‐metal centres. Two model complexes have been employed, namely, ferrocene and chromium benzene tricarbonyl. Benchmark data obtained from extrapolation of MP2 energies to the basis set limit, coupled with CCSD(T) correction, indicate that coordinated aromatic rings are slightly weaker hydrogen‐bond acceptors but are significantly stronger hydrogen‐bond donors than uncomplexed rings. It is found that π⋅⋅⋅π stacking to a second benzene is stronger than in the free benzene dimer, especially in the chromium case. This is assigned, by use of energy partitioning in the local correlation method, to dispersion interactions between metal d and benzene π orbitals. The benchmark data is also used to test the performance of more efficient theoretical methods, indicating that spin‐component scaling of MP2 energies performs well in all cases, whereas various density functionals describe some complexes well, but others with errors of more than 1 kcal mol −1 .