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

作者：Yu Li Juan; Sarrami Farzaneh; Karton Amir^*; O'Reilly Robert J

来源：Molecular Physics, 2015, 113(11): 1284-1296.

DOI：10.1080/00268976.2014.986238

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

We introduce a representative database of 22 alpha,beta- to beta,gamma-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 pi-system. The considered enecarbonyls involve a range of common functional groups (e.g., Me, NH2, OMe, F, and CN). Apart from pi-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 pi-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).

• 出版日期2015-6-3