Class Summary 11/22/04

11/22 Wave Functions for Biradicals

When is a biradical a biradical?

Controversial

An ill defined spectrum exists for purely biradical vs. purely closed-shell character

For pure closed-shell character, the overlap must be 100%, and this is never the case

For pure open-shell character, the overlap must be 0, suggesting that the two electrons in question must be an infinite distance apart from each other, also never the case.

We must consider a paradigm where we can describe something as “mostly biradical” or “mostly closed-shell”. More next day!

Relevant reference (the BIBLE of biradicals)

Salem, L, and Rowland, C. Electronic properties of diradicals Angew. Chem. Int. Ed. Engl. (1972) 11, 92 – 111.

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