Inter-isomeric equilibrium

There is still another aspect to be considered. The fullerene and metallofullerene production is not always close to the inter-isomeric equilibrium. This factor may be pertinent to the La C82 case. Lian et al. [375] reported a Ni-catalyzed production of La Cg2 with a considerably variable isomeric ratio, indicating a possible kinetic control. 

The determination that the cis and trans isomers of 1,2-d2-cyclopropane could be inter-converted thermally prompted experimental work on similar reactions exhibited by other substituted cyclopropanes to define activation parameters for representative instances of the isomerization and to begin to discriminate among alternative mechanistic suggestions. The 1,2-dimethyl- and 1-ethyl-2-methylcyclopropanes, for examples, were shown to approach cis, trans equilibrium with activation parameters log A, Ed (kcal mol"1) of 15.25, 59.4 and 15.08, 58.91 140. 

Tautomerism.—While therefore these three cyanogen compounds do not exist in isomeric forms as do the alkyl cyanogen compounds yet we cannot assign one definite formula to each compound because the evidence goes to show that sometimes one formula and sometimes the other is the true representation of the constitution. The two forms probably exist together in equilibrium the conditions of which are different for each of the compounds so that though they are very similar in character their apparent constitution is different. Thus we have another inter-... 

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