Dodecahedrane has 12 faces, right?

So there was this guy called Euler, and he had a formula that goes something like F = E - V + 2. Well, actually it is χ = V - E + F, where χ is the Euler characteristic, and this is equal to 2 for polyhedra. Anyway, the point is that dodecahedrane has 12 faces (cycles).

For the SSSRFinder, however, it has only 11; which is annoying. Moreover the ring equivalence class method only distinguishes based on the underlying simple graph - in other words it ignores bond order. In some applications this might be exactly what is needed, but I'm glad that my method gives a more detailed result:

So, apart from being a ridiculously detailed image, the above shows the face (ring, cycle) equivalence classes for dodecahedrane with a particular double bond network. Clearly any face could be 'glued' to another along one of the edges, following the vertex classes. All possible combinations of faces are shown in the 'face quotient graph' at the bottom right.

Comments

Egon Willighagen said…

12 faces = 11 bonds to cut to remove all cycles... I think the SSSR is build around the latter concept. alpha-pinene has three unique cycles, but only two bonds to cut, and two a SSSR of size two?

20 December 2010 at 19:44

gilleain said…

I really should read the papers that the code references. What I suspect is happening is that the SSSRFinder is properly implemented, but that the algorithm doesn't work the way I expect it to. Oh, and I checked and yes alpha-pinene does have 2 rings in its SSSR.

20 December 2010 at 20:22

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