Event

"Revealing the chemistry in quantum chemistry: from diatomics to proton-coupled electron transfer in enzymes"

- With quantum chemistry, nowadays most physical properties of molecules

can be easily and (often) accurately calculated—for example, DFT

calculations of molecular structure, reaction mechanisms, and reaction

energetics have become routine complements to organic chemistry.

However, the techniques behind these calculations afford no easy way of

"making sense" of the computed quantities, like orbitals and wave

functions. Additionally, many central empirical concepts of chemistry,

including concepts as basic as partial charges, bond orders, or even

covalent bonds themselves, have no consensus physical definition.

We here argue that, once we properly define what is an "atomic orbital"

in a molecule, quantities representing most other empirical concepts

can be straightforwardly derived from simple physical arguments, and

then easily calculated. In this sense, we show how our Intrinsic Atomic

Orbital (IAO) technique gives rise to partial charges and bond orders,

and to bond orbitals, which represent the electron pairs of Lewis

structures (σ- and π-bonds). Even curly-arrow reaction mechanisms can

be readily derived!

Based on selected examples, we how IAOs allow the analysis of bonding

in novel and exotic chemical species, and how the method played a key

role in understanding metal-catalyzed reaction mechanisms.

https://chem.psu.edu/directory/guk15