Force Constant, Bond Energies, Bond Strength, and Whatsoever

Abstract: The concept of the chemical bond is perhaps the most central in chemistry. It is so fundamental that the very definition of a chemical species requires the presence of chemical bonds. A chemical transformation or reaction is essentially a consequence of the reorganization of these bonds within the chemical species. This reorganization typically involves the breaking of some bonds and the formation of new ones. Understanding chemical reactivity requires careful consideration of the factors that govern the breaking of bonds, which largely depends on the amount of energy required to break that particular bond. As such, concepts like bond energy, bond strength, and bond dissociation energies are crucial in chemistry. There exist a variety of methodologies for measuring or calculating these parameters. Despite of this, there remains a need for the development of simple and reproducible methods that can accurately determine the strength of a chemical bond. Advancements in this area are essential for improving our understanding and application of chemical principles. Recent discussions in the scientific literature have highlighted that commonly used parameters — such as bond dissociation energy and bond distance — must be applied with caution if one is to accurately quantify the force of a bond. These parameters can sometimes lead to misinterpretation if not used appropriately. In this communication, recent approaches for quantifying the force of a bond are discussed. A particular methodology is presented, which relies on the curvature of the bond dissociation curve. The method offers a straightforward way to quantify and compare the relative force of different bonds. Keywords: Chemical bond; bond energy; bond dissociation; bond strength; curvature Suggested Reading: [1] D. Cremer, A. Wu, A. Larsson, and E. Kraka, “Some Thoughts about Bond Energies, Bond Lengths, and Force Constants”, J. Mol. Model., 2000, 6, 396-412.[2] L. Zhao, M. Zhi, G. Frenking, “The strength of a chemical bond”, Int. J. Quant. Chem., 2022, 122, e26773.[3] H. Borgman, S. Vasisth, J. Grunenberg, “Effective Computation of Coupling Force Constants: Metal Carbonyls as a Test Case”, J. Chem. Theory Comput., 2025, 21, 18.[4] S. Kozuch, “Do we know the chemical bond? A case for the ethical teaching of undefined paradigms”, Chemistry Teacher International, 2024, 6, 445–462.