An assessment of theoretical procedures for π -conjugation stabilisation energies in enones

Li Juan Yu, Farzaneh Sarrami, Amir Karton, Robert J. Oreilly

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

We introduce a representative database of 22 α,β- to β,γ-enecarbonyl isomerisation energies (to be known as the EIE22 data-set). Accurate reaction energies are obtained at the complete basis-set limit CCSD(T) level by means of the high-level W1-F12 thermochemical protocol. The isomerisation reactions involve a migration of one double bond that breaks the conjugated π-system. The considered enecarbonyls involve a range of common functional groups (e.g., Me, NH2, OMe, F, and CN). Apart from π-conjugation effects, the chemical environments are largely conserved on the two sides of the reactions and therefore the EIE22 data-set allows us to assess the performance of a variety of density functional theory (DFT) procedures for the calculation of π-conjugation stabilisation energies in enecarbonyls. We find that, with few exceptions (M05-2X, M06-2X, BMK, and BH&HLYP), all the conventional DFT procedures attain root mean square deviations (RMSDs) between 5.0 and 11.7 kJ mol-1. The range-separated and double-hybrid DFT procedures, on the other hand, show good performance with RMSDs below the chemical accuracy threshold. We also examine the performance of composite and standard ab initio procedures. Of these, SCS-MP2 offers the best performance-to-computational cost ratio with an RMSD of 0.8 kJ mol-1.

Original languageEnglish
Pages (from-to)1284-1296
Number of pages13
JournalMolecular Physics
Volume113
Issue number11
DOIs
Publication statusPublished - Jun 3 2015

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Keywords

  • CCSD(T)
  • density functional theory
  • enones
  • isomerisation energies
  • π-conjugation

ASJC Scopus subject areas

  • Biophysics
  • Molecular Biology
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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