Re: resonance



Hi, John,


You probably don't want to know this, but resonance theory is wrong.

Cyclobutadiene has exactly as many resonance forms as benzene, but it
is extremely unstable. Cyclooctatetraene escapes instability only
because it can deform out of the plane to minimize the overlap between
orbitals, and its double bonds are as reactive as those in ethene. And
so on.

Resonance theory was put forward by Pauling based on intuition, and was
never justified in terms of basic quantum mechanics. If you want to
know how it can be done properly, read 'The PMO Theory of Organic
Chemistry' by M.J.S. Dewar. I think there are a couple of books by
Dewar with more-or-less that title: the last one is best. Resonance
theory does get a few things right, by a fluke, and Dewar explains why.

So the question of how many resonance forms CH3COO- has is akin to the
question of how many angels can dance on the head of a pin.


Cheers,

Zigoteau.

.

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