Theoretical studies of the inversion barrier in corannulenes
- City Univ. of New York, Flushing, NY (United States)
Ab initio energies and geometries of symmetrical corannulenes having carbons selectively substituted by heteroatoms are reported. It is found that substitution can greatly affect the inversion barrier; pentaazocorannulene has a barrier 8 times that of corannulene, while in pentaborazacorannulene it is less than 1 kcal/mol. A very small barrier is also found for the tetraanion of corannulene. For corannulene itself, vibrational frequencies are reported for its equilibrium bowl (C[sub 5v]) and planar (D[sub 5h]) forms at the 6-31G SCF level. All 84 vibrational frequencies of the bowl form are real. Planar corannulene has one imaginary (A[double prime][sub 2]) frequency, strongly suggesting that it is the transition state for bowl-to-bowl inversion. The energies, vibrational frequencies, and moments of inertia provide estimates of the enthalpy and free energy of activation for inversion. T[Delta]S[double dagger] is positive and ca. 12% of [Delta][sup [degrees][sub f,298]] at 298 K. [Delta]H[sup [degrees][sub f,298]] of corannulene is calculated to be 122.1 kcal/mol. 15 refs., 2 figs., 3 tabs.
- OSTI ID:
- 7301943
- Journal Information:
- Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 116:4; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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400201* -- Chemical & Physicochemical Properties
664100 -- Theory of Electronic Structure of Atoms & Molecules-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ACTIVATION ENERGY
AROMATICS
CALCULATION METHODS
CARBON
COMPILED DATA
CONFORMATIONAL CHANGES
DATA
ELEMENTS
ENERGY
ENERGY LEVELS
ENTHALPY
EXCITED STATES
FREE ENERGY
FULLERENES
HETEROCYCLIC COMPOUNDS
INFORMATION
MATHEMATICAL MODELS
MOLECULAR STRUCTURE
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
VIBRATIONAL STATES