title: [5]Radialene.
abstract: The [n]radialenes are a unique family of fundamental [n]-membered carbocyclic structures with radiating alkenes, which have attracted significant synthetic and theoretical attention. Whereas [3]-, [4]-, and [6]radialenes have been prepared and studied, all efforts to synthesize the five-membered ring compound have thus far met with failure. Here we describe the first synthesis of the fundamental hydrocarbon [5]radialene, C10H10. Our approach was a departure from previous radialene syntheses in that it utilized a low-temperature decomplexation of a stable organometallic compound, rather than high-temperature elimination or rearrangement. Our strategy was guided by analysis of previous radialene syntheses, which indicated rapid decomposition in oxygen, and ab initio calculations, which revealed an extraordinary susceptibility of [5]radialene to undergo Diels-Alder dimerization/polymerization. The origin of this susceptibility was traced to a small distortion energy associated with the formation of the transition structure geometry from the relaxed reactant monomers and to a narrow HOMO-LUMO gap.
authors.affiliation: Research School of Chemistry, Australian National University , Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Emily G
authors.initials: EG
authors.lastname: Mackay
authors.affiliation: Research School of Chemistry, Australian National University , Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Newton
authors.affiliation: Research School of Chemistry, Australian National University , Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Henry
authors.initials: H
authors.lastname: Toombs-Ruane
authors.affiliation: Research School of Chemistry, Australian National University , Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Erik Jan
authors.initials: EJ
authors.lastname: Lindeboom
authors.affiliation: Research School of Chemistry, Australian National University , Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Thomas
authors.initials: T
authors.lastname: Fallon
authors.affiliation: Research School of Chemistry, Australian National University , Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Willis
authors.affiliation: School of Chemistry, The University of New South Wales , Sydney, New South Wales 2052, Australia.
authors.forename: Michael N
authors.initials: MN
authors.lastname: Paddon-Row
authors.affiliation: Research School of Chemistry, Australian National University , Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Sherburn