Conformation and Crystal Packing of Trans-1,4 Substituted Cyclohexanes. G. Echeverría^*, Y. G. Punte, Profimo Y Lanadi. Dpto. de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata. C.C.67 - (1900) La Plata. Argentina(*) also with Fac de Ingeniería, UNLP, (1900) La Plata

Trans-1,4-dibromo-1,4-dicarboxy- (I), Trans-1,4-dicarboxymethyl- (II) and Trans-1,4-dibromo-1,4-dicarboxymethylcyclohexane (III) have been study by single crystal X-ray diffraction at different temperatures.

Significant departure of C-C bond lengths from the ideal cyclohexane value were observed in I. To rationalize this result and to analyze the influence of the substituents and the interaction between them on the cyclohexane conformation, hydrogen bond patterns and Br ordering, ab-initio calculations were performed. The optimized conformation and the electrostatic properties of I, II and III along with supramolecular dimer optimization of model systems were obtained. The correlation between experimental data and calculation results allows to explain some of the experimental findings.