THERMOCHEMICAL STUDY OF SOME CUBANE DERIVATIVES

The thermochemical study of cubane-1,4-dicarboxylic acid (1), diethyl cubane-1,4-dicarboxylate (2), diisopropyl cubane-1,4-dicarboxylate (3) , and bis(2-fluoro-2,2-dinitro)ethyl cubane-1,4-dicarboxylate (4) was performed. The standard enthalpies of combustion (Delta(c)H degrees) a nd formation (Delta(f)H degrees) of these compounds were estimated usi ng the method of combustion in a calorimetric bomb in an oxygen atmosp here. Using the additive group method, calculated values for Delta(f)H degrees of these substances which agreed satisfactorily with the expe rimental ones were obtained. The strain energies (E(S)) of the cubic s tructure of derivatives 1-4 were calculated. It was concluded that E(S ) did not change on substitution of hydrogen atoms in cubane for vario us functional groups and was equal to E(S) of the structure of cubane itself. The reliability of the single published value of Delta(f)H deg rees in the cubane crystal state, 541.8 kJ mol(-1) (129.5 kcal mol(-1) ), was confirmed.