Davidane, a polycyclic alkane of significant chemical and notable iconic interest: a computational study

This paper reports the results of ab initio calculations on the geometry and the kinetic and thermodynamic stability of a hydrocarbon, the molecular structure of which, in planar projection, resembles a symbol best known as the iconic Star of David. This C 12 H 12 structure consists of a central cyclohexane ring with six pendant cyclopropane rings; six of the carbons are quaternary and six are CH 2 carbons. The formal rules for naming polycyclic molecules result in the name heptacyclo[9.1.0.0 1,3 .0 3,5 .0 5,7 .0 7,9 .0 9,11 ]dodecane; the name davidane is suggested as a convenient and euphonious alternative. Reasonably high-level ab initio calculations (CCSD(T)/6-31G * //MP2/6-31G * ) indicate that the C 12 H 12 potential energy surface with the davidane connectivity holds two relative minima, a lower-energy molecule with D 3d symmetry and a much higher-level (426 kJ mol −1 ) configurational isomer with C 2 symmetry. A valence isomeric shift can convert the lower-energy isomer into a triene with the same connectivity 55.5 kJ mol −1 lower, through a transition state representing a 169 kJ mol −1 barrier.