10.1021/jacs.5b12434.s001 Martin Rahm Martin Rahm Roald Hoffmann Roald Hoffmann Distinguishing Bonds American Chemical Society 2016 electron binding energy multielectron interactions term VNN bond 2016-02-24 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Distinguishing_Bonds/3101455 The energy change per electron in a chemical or physical transformation, Δ<i>E</i>/<i>n</i>, may be expressed as Δχ̅ + Δ­(<i>V</i><sub>NN</sub> + ω)/<i>n</i>, where Δχ̅ is the average electron binding energy, a generalized electronegativity, Δ<i>V</i><sub>NN</sub> is the change in nuclear repulsions, and Δω is the change in multielectron interactions in the process considered. The last term can be obtained by the difference from experimental or theoretical estimates of the first terms. Previously obtained consequences of this energy partitioning are extended here to a different analysis of bonding in a great variety of diatomics, including more or less polar ones. Arguments are presented for associating the average change in electron binding energy with covalence, and the change in multielectron interactions with electron transfer, either to, out, or within a molecule. A new descriptor <i>Q</i>, essentially the scaled difference between the Δχ̅ and Δ­(<i>V</i><sub>NN</sub> + ω)/<i>n</i> terms, when plotted versus the bond energy, separates nicely a wide variety of bonding types, covalent, covalent but more correlated, polar and increasingly ionic, metallogenic, electrostatic, charge-shift bonds, and dispersion interactions. Also, Q itself shows a set of interesting relations with the correlation energy of a bond.