Three-Membered Rings, frames

You might reasonably have said stereochemistry, but the best answer is the three membered ring. Which three carbene discormections might we consider (See frames 276-288 if you ve forgotten all tliis ). 

Most probably, the different coordination of Cd in the three groups of zeohtes is responsible for the different increase of activity with the Si/Al ratio. The same bivalent cation coordination to the six-membered ring with similar distances between the cation and frame-... 

A last important feature concerns the bicyclic species. Our calculations show that their formation is favoured when both constitutive rings contain each an even number of tetrahedra. The concentration of oligomers made of two four- or six-membered rings is respectively larger than the concentration of species containing two three- or five- membered rings. This behaviour is directly related to Loewenstein1 s rule and can be related to the fact that the frame-... 

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