title: Incorporation of 2-arylhexa-1,5-diene into pentasil zeolite: A distorted 1-arylcyclohexane-1,4-diyl radical cation at room temperature.
abstract: Incorporation into a redox-active pentasil zeolite [(Na,H)-ZSM-5] converted 2-arylhexa-1,5-dienes (9a-c; aryl = phenyl, tolyl, anisyl) into 1-arylcyclohexane-1,4-diyl radical cations, 10a-c*+. The ESR spectra of 10a-c*+ (six lines, g = 2.0026; a = 9.0 G) indicated the presence of five essentially equivalent nuclei, indicating limited delocalization of spin and charge into the phenyl group. Sequestered in the pores of ZSM-5, the three species 10a-c*+ are stable at room temperature, in striking contrast to the parent radical cation in cryogenic matrices: cyclohexane-1,4-diyl radical cation is converted to cyclohexene radical cation above 90 K. The structures of radical cation 10a*+ (X = H) and of the unsubstituted parent were probed by density functional theory (DFT) and ab initio calculations.
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ikeda
authors.forename: Tomonori
authors.initials: T
authors.lastname: Minegishi
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Miyashi
authors.forename: Prasad S
authors.initials: PS
authors.lastname: Lakkaraju
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Sauers
authors.forename: Heinz D
authors.initials: HD
authors.lastname: Roth