TRANS-1,3,5,7-TETRAOXADECALIN VERSUS CIS-1,3,5,7-TETRAOXADECALIN - A STRUCTURAL, THERMOCHEMICAL, AND COMPUTATIONAL STUDY

In a multidisciplinary study (low-temperature X-ray diffraction, heats of combustion, and high-level (MP2/6-31+G) ab initio calculations), the structure and relative stability of trans-1,3,5,7-tetraoxadecalin (I)versus its cis-diastereomer (2) were established. We also calculate d the atomic charges and proton affinities of the oxygen sites to pred ict the probable coordination sites in each isomer. Excellent agreemen t was found between the experimental and theoretical structural parame ters, which were well reproduced by force field calculations using MM3 -GE (MM3 reparametrized for the gauche effect). Also, 1 and 2 are larg ely equienergetic within experimental errors and the computational met hods used.