Cyclopentacorannulene: {pi}-facial stereoselective deuterogenation and determination of the bowl-to-bowl inversion barrier for a constrained buckybowl
- Louisiana State Univ., Baton Rouge, LA (United States)
Attachment of an ethane or ethylene unit to the rim of corannulene produced relatively rigid bowls of dihydrocyclopenta- and cyclopentacorannulene, respectively. In contrast to the parent corannulenes, their inversion barriers are too high to be determined by the NMR coalescence methods. Due to the significant curvature of cyclopentacorannulene, deuterogenation is {pi}-facial specific; both heterogeneous and homogeneous catalysis lead exclusively to exo-dideuteriocyclopentacorannulene 2a. Equilibration of the endo- and exo-isotopomers allowed the determination of {Delta}G{sup {dagger}} at 27.61-27.67 kcal/mol over the temperature range 52.1-99.3{degree}C and the estimation of {Delta}H{sup {dagger}} (27.3{+-}0.7 kcal/mol) and {Delta}S{sup {dagger}} (-1.1{+-}0.2 eu) for the bowl-to-bowl inversion. The inversion barrier calculated at the HF/6-31G{sup *}//3-21G level (25.9 kcal/mol) compares well with the experimental result. 20 refs., 3 figs., 1 tab.
- OSTI ID:
- 199420
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 2 Vol. 118; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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