Theoretical study of iodine compounds: Enthalpies of formation

A systematic study was performed to examine the possibilities method of G4(MP2)-XK and functionals M06, M06-HF, M06-2X, BMK, wB97XD, PBE1PBE, B2PLYP, B2GP-PLYP, DSD-PBEP86, B3LYP and TPSSh with the basis sets def2-TZVP and def2-QZVP, including a pseudopotential def2-ECP, CRENBL-ECP, and CRENBS-ECP for iodine compounds. The G4MP2-XK method presented the best results in this work with the molecules that were studied with a MAE of 4.2 kcal mol-1. G4(MP2)-XK showed better results when compared to other composite methods, like G3(MP2)/B3-SBK and G2. The major deviation from the experimental for the functionals studied in this work occurs with molecules that include iodine haloalkanes. The best functional was wB97XD with a def2-QZVP basis set with CRENBS-ECP having a MAE of 12.6 kcal mol-1. We recommend the G4MP2-XK method and G3(MP2)//B3-SBK functional for applications involving thermochemistry with iodine compounds.