The current experimental and computational research in carbon clusters pointed out a need for enumeration of all possible12C/13C isotopoments of the C2v cyclic odd-numbered carbon clusters Cn. It is shown that the number of the isotopomers is given by 2k–1(2k–1+1) withk=(n+1)/2. Some illustrative computed structure and energy data for the clusters are reported, too.
Isotopic rules are studied for calculated vibrational frequencies of all possible 7212C/13C isotopomers of the C7 cluster of the C2v symmetry. The isotopomers can undergo 486 isomerizations which are decomposed into 27 subclasses using properties of sums of the squares of the vibrational frequencies.
The set of all 51 possible12C/13C isotopomers of a C8 cluster of D2d symmetry has been studied by means of the harmonic vibration analysis based on the force field resulting from the second order Møller-Plesset (MP2) perturbation treatment with the 6-31G* basis set. The isotopomers can undergo 200 isomerizations which can be classified into 5 distinct groups using the properties of sums of the squares of harmonic vibrational frequencies.