Publication: Singlet-triplet excitation energies of substituted benzenes: A G4 theoretical study

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Title	Singlet-triplet excitation energies of substituted benzenes: A G4 theoretical study
Authors/Editors*	S Rayne, K Forest
Where published*	Nature Precedings
How published*	Other
Year*	2011
Volume
Number
Pages
Publisher	Nature Publishing Group
Keywords	Phenyl cations; Substituent effects; Singlet-triplet excitation energies; Ground state multiplicity
Link	http://dx.doi.org/10.1038/npre.2011.6449.1
Abstract	Singlet-triplet adiabatic (AES-T) and well-to-well (WWES-T) excitation energies of variously substituted phenyl cations were calculated at the G4 level of theory. The G4 ES-T estimates range from 19 to 40 kJ/mol higher than prior density functional theory based predictions for these cations, and suggest that ES-T and ground state multiplicity structure-property trends for phenyl cations previously proposed in the literature may be incorrect. Among the substituents considered, meta-substituted phenyl cations with electron donating groups have singlet ground states, and are not isoenergetic with the corresponding triplet states as previously claimed. Depending on the functional group, ortho- or para- substituted phenyl cations may also be ground state singlets despite the presence of an electron donating moiety.