Determination of the Minimum Energy Conformation of Allylbenzene and Its Clusters with Methane, Ethane, Water and Ammonia
COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
Pagination or Media Count:
Supersonic molecular jet laser time of flight mass spectroscopy TOFMS is employed to determine the minimum energy conformation of the allyl group with respect to the benzene ring of allylbenzene, 1-allyl-2-methylbenzene and 1-allyl-3-methylbenzene. The spectra are assigned and conformations are suggested with the aid of molecular orbital molecular mechanics MOMM-85 calculations. Based on the experimental and theoretical results, the minimum energy conformer is found to have tau1 Cortho-Cipso-Calpha-C-beta ca. 90 degs i.e., the allyl group is essentially perpendicular to the plane of the benzene ring and tau2Cipso-Calpha-Cbeta-Cgamma or - 120 degs i.e., the olefin CC bond is eclipsed with the Calpha-Halpha bond. The TOFMS of allylbenzene clustered with methane, ethane, water and ammonia are also presented. A Lennard-Jones potential energy 6-12-1 atom-atom calculation is used to characterize the structures of these clusters. Experiments and calculations demonstrate that the four different solvent molecules studies can form stable clusters with allylbenzene by coordinating to the Pi-system of allyl substituent in addition to that of the aromatic ring.
- Organic Chemistry