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

• Published in: International journal of quantum chemistry Vol. 119; no. 21
• Main Authors: Afonin, Andrei V., Vashchenko, Alexander V.
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 05.11.2019; Wiley Subscription Services, Inc
• Subjects: Aliphatic compounds; Benchmarks; Bond energy; bond energy estimation; Bond strength; Chemical bonds; Chemistry; Dependence; Energy; Error compensation; Estimation; Fragmentation; function‐based approach; Hydrogen bonds; Hydrogen-based energy; hydroxycarbonyl aliphatic compounds; intramolecular hydrogen bond; Mathematical analysis; modified Espinosa's equation; molecular tailoring approach; Parameter estimation; Physical chemistry; Quantum physics
• ISSN: 0020-7608; 1097-461X
• DOI: 10.1002/qua.26001

The 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. Two basic methods for estimating the energy of intramolecular hydrogen bonds (molecular tailoring and function‐based approaches) are compared using a series of the hydroxycarbonyl aliphatic compounds as the benchmark. Functional dependencies are established that match with molecular fragmentation method. New hybrid approach as combination of molecular tailoring and function‐based approaches is proposed to assess the intramolecular hydrogen bond energy in the benchmarked molecules.