55836-31-2Relevant articles and documents
Electron Paramagnetic Resonance Spectra of the Radical Cations of Some Benzocyclobutenes, Benzocyclopentenes and Benzocyclohexenes
Avila, David V.,Davies, Alwyn G.,Li, Elizabeth R.,Ng, Kai M.
, p. 355 - 362 (2007/10/02)
1,2,4,5-Tetrahydrobenzodicyclobutene, 1,2,3,5,6,7-hexahydrobenzodicyclopentene and 1,2,3,4,6,7,8,9-octahydrobenzodicyclohexene, and their dimethyl derivatives, and tetramethylbenzocyclo-butene, -pentene and -hexene have been prepared.All except the first compound have been oxidised to their corresponding radical cations, and the EPR spectra have been analysed by assigning McConnell-type Q-values to the substituents in the benzene ring.It is suggested that the ordering of the orbital energy levels (ΨA above ΨS) in 3,6-dimethylbenzobiscyclobutene and -pentene is a manifestation of the Mills-Nixon effect, and results from rehybridisation of the strained molecular framework.In the radical cations of 5,10-dimethyl-1,2,3,4,6,7,8,9-octahydrobenzodicyclohexene and 5,6,7,8-tetramethyl-1,2,3,4-tetrahydrobenzocyclohexene the total unpaired electron density, as implied by the McConnell type of relationship, appears to be less than unity.Various possible causes of this are examined.
