Biradicals potential energy surfaces

The combination is in this case an out-of-phase one (Section I). This biradical was calculated to be at an energy of 39.6 kcal/mol above CHDN (Table ni), and to lie in a real local minimum on the So potential energy surface. A normal mode analysis showed that all frequencies were real. (Compare with the prebenzvalene intermediate, discussed above. The computational finding that these species are bound moieties is difficult to confimi experimentally, as they are highly reactive.)... 

Figure 7.24. Schematic representation of energies of stationary points for the Norrish type 11 reaction of butanal. The diagram corresponds to a projection of multidimensional potential energy surfaces into a plane. The two energies given for the biradical on the S, suiface correspond to a geometry optimized for So (front bottom) and optimized for S, (middle rear), respectively. A broken...

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