Benchmark calculations of intramolecular hydrogen bond energy based on molecular tailoring and function‐based approaches: Developing hybrid approach

Abstract

AbstractThe energy of the intramolecular hydrogen bond has been recognized and may be estimated by the molecular fragmentation method and the method based on the functional dependence on the hydrogen bond descriptor. Both basic methods for estimating the energy of intramolecular hydrogen bonds are compared using a series of the hydroxycarbonyl aliphatic compounds as the benchmark. The functional dependencies are established that provide the best fit with the molecular fragmentation method. As both methods for estimating the energy of an intramolecular hydrogen bond have disadvantages, a new hybrid approach is proposed. In this approach, the average value of the intramolecular hydrogen bond energy calculated by the molecular fragmentation method and functional dependence method is used as the estimated parameter. The hybrid approach provides a compensation of the error in the evaluation of the interaction strength compared to the molecular fragmentation method or the functional dependencies method. Hence, it allows one to more reliably rank the strength of the intramolecular hydrogen bond in homogeneous series of molecules. Based on this approach, the strength of the О−Н···О=C intramolecular hydrogen bond in the studied compounds are classified in the energy scale in terms of weak, moderate, and strong interactions.