Theoretical study of the thermochemistry of Formation, acidity and basicity of 2- and 8-Hydroxy azaazulene and their mercapto analogues

Abstract

The gas phase standard enthalpies of formation ΔfHgas° for the tautomers and rotamers of 2- and 8-hydroxy azaazulene and their mercapto analogues have been estimated at B3LYP/6–311 + G(d,p) and M06-2X/6–311++G(2d,2p) levels of theory. The G3MP2 composite method has also been utilized to obtain more accurate correlated computational results. By using atomization and isodesmic reactions, it has been possible to calculate the theoretical enthalpies of formation for the structures under study. Depending on the enthalpies of formation results, the stability of the examined tautomers and rotamers has been discussed. The gas-phase basicity (GB), proton affinities (PA) of the N and O/S atoms, and the deprotonation enthalpies (DPE) of the NH and OH/SH bonds for the investigated system have been determined at the three levels of theory as well.