Electronic structure benchmark calculations of inorganic and biochemical carboxylation reactions

• Published in: Journal of computational chemistry 2019-05, Vol.40 (13), p.1401-1413
• Main Authors: Douglas‐Gallardo, Oscar A., Saez, David Adrian, Vogt‐Geisse, Stefan, Vöhringer‐Martinez, Esteban
• Format: Article
• Language: English
• Subjects: Biochemistry; Carbon dioxide; Carboxylation; Chemical reactions; Correlation; coupled‐cluster calculations; Density functional theory; electronic correlation energy; Electronic properties; Electronic structure; electronic structure calculations; inorganic and biochemical carboxylation reactions; Mathematical analysis; Molecular orbitals; Organic chemistry
• ISSN: 0192-8651; 1096-987X
• DOI: 10.1002/jcc.25795

Carboxylation reactions represent a very special class of chemical reactions that is characterized by the presence of a carbon dioxide (CO2) molecule as reactive species within its global chemical equation. These reactions work as fundamental gear to accomplish the CO2 fixation and thus to build up more complex molecules through different technological and biochemical processes. In this context, a correct description of the CO2 electronic structure turns out to be crucial to study the chemical and electronic properties associated with this kind of reactions. Here, a systematic study of CO2 electronic structure and its contribution to different carboxylation reaction electronic energies has been carried out by means of several high‐level ab initio post‐Hartree Fock (post‐HF) and density functional theory (DFT) calculations for a set of biochemistry and inorganic systems. We have found that for a correct description of the CO2 electronic correlation energy it is necessary to include post‐CCSD(T) contributions (beyond the gold standard). These high‐order excitations are required to properly describe the interactions of the four π‐electrons associated with the two degenerated π‐molecular orbitals of the CO2 molecule. Likewise, our results show that in some reactions it is possible to obtain accurate reaction electronic energy values with computationally less demanding methods when the error in the electronic correlation energy compensates between reactants and products. Furthermore, the provided post‐HF reference values allowed to validating different DFT exchange‐correlation functionals combined with different basis sets for chemical reactions that are relevant in biochemical CO2 fixing enzymes. © 2019 Wiley Periodicals, Inc. Schematic representation of the electronic correlation energy for reactants and products in two representative carboxylation reactions. The height of each box represents the total electronic correlation energy calculated at CBS limit and the respective color shows the amount recovered by a specific electronic structure method. Errors in the calculated reaction energies are much larger when no error compensation between reactants and products takes place.