Intramolecular hydrogen bond energy in polyhydroxy systems: a critical comparison of molecular tailoring and isodesmic approaches.
The intramolecular hydrogen bond (H-bond) energies in several polyhydroxy systems are estimated using an isodesmic/homodesmic reaction approach as well as a molecular tailoring approach (MTA) [Deshmukh, M. M.; Gadre, S. R.; Bartolotti, L. J. J. Phys. Chem. A 2006, 110, 12519]. It is shown that the isodesmic/homodesmic reaction approach as advocated in the literature does not give true H-bond energy but includes the effect of strain energy due to the formation of a ring structure. Such a ring strain is duly accounted for in the MTA method. The isodesmic H-bond energies are found to be smaller than their MTA energy counterparts typically by the strain energy. The MTA is applied to decitol, a system with more than five different H-bonds for which an application of an appropriate isodesmic reaction is extremely difficult. It has been shown that the MTA method is able to predict not only the H-bond energies but also the trends in conformational energies for three different conformers of decitol studied in the present work.
Deshmukh
Milind M
MM
Department of Chemistry, University of Pune, Pune 411 007, India.
Suresh
Cherumuttathu H
CH
Gadre
Shridhar R
SR
D000438:Alcohols / Q000737:chemistry*; D002627:Chemistry, Physical / Q000379:methods*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D015394:Molecular Structure; D011789:Quantum Theory; D013816:Thermodynamics
D000438:Alcohols