title: All-cis 1,2,3,4,5,6-hexafluorocyclohexane is a facially polarized cyclohexane.
abstract: The highest-energy stereoisomer of 1,2,3,4,5,6-hexafluorocyclohexane, in which all of the fluorines are 'up', is prepared in a 12-step protocol. The molecule adopts a classic chair conformation with alternate C-F bonds aligned triaxially, clustering three highly electronegative fluorine atoms in close proximity. This generates a cyclohexane with a high molecular dipole (μ = 6.2 D), unusual in an otherwise aliphatic compound. X-ray analysis indicates that the intramolecular Fax···Fax distances (∼2.77 Å) are longer than the vicinal Fax···Feq- distances (∼2.73 Å) suggesting a tension stabilizing the chair conformation. In the solid state the molecules pack in an orientation consistent with electrostatic ordering. Our synthesis of this highest-energy isomer demonstrates the properties that accompany the placement of axial fluorines on a cyclohexane and the unusual property of a facially polarized ring in organic chemistry. Derivatives have potential as new motifs for the design of functional organic molecules or for applications in supramolecular chemistry design.
authors.affiliation: EaStCHEM School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK.
authors.forename: Neil S
authors.initials: NS
authors.lastname: Keddie
authors.affiliation: EaStCHEM School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK.
authors.forename: Alexandra M Z
authors.initials: AM
authors.lastname: Slawin
authors.affiliation: EaStCHEM School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK.
authors.forename: Tomas
authors.initials: T
authors.lastname: Lebl
authors.affiliation: EaStCHEM School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK.
authors.forename: Douglas
authors.initials: D
authors.lastname: Philp
authors.affiliation: EaStCHEM School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK.
authors.forename: David
authors.initials: D
authors.lastname: O'Hagan