title: Cobalt-mediated synthesis of angular [4]phenylene: structural characterization of a metallacyclopentadiene(alkyne) intermediate and its thermal and photochemical conversion.
abstract: [reaction: see text] The first X-ray crystal structure of a mononuclear metallacyclopentadiene(alkyne) complex has been obtained. This type of metallacycle is believed to be the key intermediate in the cobalt-mediated [2 + 2 + 2]cycloaddition of alkynes. Thermal treatment leads to the generation of angular [4]phenylene, the X-ray structural details of which are described. Under photochemical conditions, the cobaltacycle isomerizes to a highly strained (cyclobutadieno)dibenzocyclooctatrienyne complex.
authors.affiliation: CLRC Daresbury Laboratory, Warrington, Cheshire, WA4 4AD, UK.
authors.forename: Peter I
authors.initials: PI
authors.lastname: Dosa
authors.forename: Glenn D
authors.initials: GD
authors.lastname: Whitener
authors.forename: K Peter C
authors.initials: KP
authors.lastname: Vollhardt
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Bond
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Teat