Toward an Experimental Quantum Chemistry: Exploring a New Energy Partitioning

Journal article, 2015

Following the work of L. C. Allen, this work begins by relating the central chem. concept of electronegativity with the av. binding energy of electrons in a system. The av. electron binding energy, ̅χ, is in principle accessible from expt., through photoelectron and X-ray spectroscopy. It can also be estd. theor. ̅χ has a rigorous and understandable connection to the total energy. That connection defines a new kind of energy decompn. scheme. The changing total energy in a reaction has three primary contributions to it: the av. electron binding energy, the nuclear-nuclear repulsion, and multielectron interactions. This partitioning allows one to gain insight into the predominant factors behind a particular energetic preference. We can conclude whether an energy change in a transformation is favored or resisted by collective changes to the binding energy of electrons, the movement of nuclei, or multielectron interactions. For example, in the classical formation of H2 from atoms, orbital interactions dominate nearly canceling nuclear-nuclear repulsion and two-electron interactions. While in electron attachment to an H atom, the multielectron interactions drive the reaction. Looking at the balance of av. electron binding energy, multielectron, and nuclear-nuclear contributions one can judge when more traditional electronegativity arguments can be justifiably invoked in the rationalization of a particular chem. event. [on SciFinder(R)]