Enumeration Theorem for Conformational Isomers

The maximum number of isometric re-structures NC (Xk( e), Zk equals l ( )l. This set of restructures decomposes for each particular isotopic modification NC Xk(f ), Zk, Mk into subsets of isomers (nonisometric NCs). Each isomer is associated with a coset of the decomposition of W ( ) modulo ( ) (e = I ( ) I,  

13 Since the problem of conformational isomerism is entirely a question of relative nuclear configuration, primitive period isometric transformations have to be omitted. 

The enumeration method outlined above will be illustrated by determining the number of isomers of various isotopic modifications of diphenylmethane CH2(C6HS)2, assuming various equilibrium values for the internal coordinates. The normal isotopic modification of this nonrigid molecule, and at the same time NC Xk(T0, t. ZiJ, may be approximated by the SRM C2 VF(C2 VT)2 another molecule of this type is dini- 

tj) of the normal isotope and therefore the group %(r0, r() is isomorphic to the point group D4h 

A NC with arbitrary r0 and Tj does not possess covering symmetry, therefore i.r0,Ti) = Cy 

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