SYNTHESIS, ISOLATION, AND EQUILIBRATION OF 1,9-C70H2 AND 7,8-C70H2

Equilibration of 1,9- and 7,8-C70H2 has allowed the relative free ener gy of these isomers to be measured. These ''simplest hydrocarbon deriv atives of C70'' are formed by hydroboration of C70 at room temperature . Analysis of the platinum-catalyzed equilibration of these isomers yi elded a relative free energy at 295 kelvin of 1.4 +/- 0.2 kilocalories per mole, with the 1,9 isomer being more stable. This value is in exc ellent agreement with the ab initio HF/6-31G calculated energy differ ence of 1.3 kilocalories per mole, whereas semiempirical calculations gave poor agreement.