Ab Initio Study of the Cyclooctatetraenyl Radical
- 30 March 2005
- journal article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry A
- Vol. 109 (15), 3391-3395
- https://doi.org/10.1021/jp046460m
Abstract
Ab initio calculations have been carried out on the 1,3,5,7- and 1,2,4,7-tetraene configurations of the cyclooctatetraenyl radical at UHF, ROHF, MCSCF, ROCISD, QCISD, and CCSD(T) levels of theory with 6-311G(d,p) and cc-pVDZ basis sets. Although spin contamination is present, the ROCISD calculations support the energies obtained from less intensive, UHF-based coupled cluster calculations over the energies obtained from MCSCF analysis of the π-electron orbitals. The 1,3,5,7-form is a local minimum at the coupled cluster levels, higher in energy than the resonance-stabilized 1,2,4,7-form by 10−13 kJ/mol, but bounded by a barrier of less than 0.5 kJ/mol. The isomerization surface connecting these two structures is described and results reported from integration of the vibrational Schrödinger equation on that surface. Excited vibrational states at energies just above the isomerization barrier are dominated by the character of the 1,3,5,7-tetraenyl radical, which suggests that chemistry involving this intermediate at typical combustion temperatures may branch at this juncture.Keywords
This publication has 34 references indexed in Scilit:
- Experimental study of fuel decomposition and hydrocarbon growth processes for cyclohexane and related compounds in nonpremixed flamesCombustion and Flame, 2004
- Formation of polycyclic aromatic hydrocarbons and soot in fuel-rich oxidation of methane in a laminar flow reactorCombustion and Flame, 2003
- Reaction of Phenyl Radicals with Acetylene: Quantum Chemical Investigation of the Mechanism and Master Equation Analysis of the KineticsJournal of the American Chemical Society, 2003
- Ab Initio Study of 1,4-Pentadienyl Electrocyclic ReactionsThe Journal of Organic Chemistry, 2002
- Relocalization in Floppy Free Radicals: The OCNO and OCCHO Isoelectronic SeriesJournal of the American Chemical Society, 2001
- Hydrogen Migration in the Phenylethen-2-yl RadicalThe Journal of Physical Chemistry A, 1999
- Ab Initio Study of the Most Stable C4H5 IsomersThe Journal of Physical Chemistry A, 1999
- Relocalization in Floppy Free Radicals: Ab Initio Calculations of the C3H3O IsomersThe Journal of Physical Chemistry A, 1998
- The Importance of Including Dynamic Electron Correlation in ab Initio CalculationsAccounts of Chemical Research, 1996
- Conjugated .pi.-Electron Systems in Reactive Molecules: Multiple Minima on 2A' Potential Surfaces of Carbon Chain Free RadicalsJournal of the American Chemical Society, 1995