Why does electronic structure matter?


Electronic structure can be used to derive lots of information concerning chemistry.

Imagine you wanted to make 2-Fluoro-Bicyclobutane. Using methods based on the theory of electronic structure, you can predict:

Its structure:

fluorobicyclobutane pic

The central Carbon-Carbon bond has a length of 1.52 Angstrom - not too stretched

Its stability. It is roughly 23 kcal/mol more stable than two possible (but not very plausible...) starting products, acetylene and fluoroethylene.

Its spectroscopy. The C-F bond has a predicted frequency of 1184 cm-1, and the normal mode looks like this:

fluorobicyclobutane animation


You can also study reactivity, for example by locating transition states. Here, you can see the reaction coordinate at the transition state of the Diels-Alder reaction:

diels-alder animation


Or you can predict reactivity by examining the orbitals of the reagents. Here, for example, is what the lowest unoccupied orbital of the Tungsten complex W(CO)5[=CH(OCH3)] looks like:

tungsten complex LUMO

Clearly, the best site for attack of a nucleophile is on the carbene carbon atom - which is exactly what is found experimentally.


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This page created by Jeremy Harvey, Bristol, 2000.