title: Synthesis of rhenabenzenes from the reactions of rhenacyclobutadienes with ethoxyethyne.
abstract: Treatment of Na[Re(CO)5 ] with RCCCO2 Et (R=phenyl, naphthalen-1-yl, phenanthren-9-yl and pyren-1-yl) followed by reaction with acetyl chloride and ethanol afforded the rhenacyclobutadienes Re{-C(R)C(CO2 Et)C(OEt)}(CO)4 . Reactions of these rhenacyclobutadienes with HCCOEt produced rhenabenzenes Re{-C(R)C(CO2 Et)C(OEt)CHC(OEt)}(CO)4 . Except for R=Ph, new rhenacyclobutadienes with pendant alkenyl substituents Re{-C(R)C(C(OEt)CH(CO2 Et))C(OEt)}(CO)4 were also isolated from these reactions. The NMR spectroscopic and X-ray structural data, as well as the aromatic stabilization energy (ASE) values suggest that the rhenabenzenes are aromatic, with extensive delocalized π character.
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong), Fax: (+852) 2358-1594.
authors.forename: Ran
authors.initials: R
authors.lastname: Lin
authors.forename: Ka-Ho
authors.initials: KH
authors.lastname: Lee
authors.forename: Ka Chun
authors.initials: KC
authors.lastname: Poon
authors.forename: Herman H Y
authors.initials: HH
authors.lastname: Sung
authors.forename: Ian D
authors.initials: ID
authors.lastname: Williams
authors.forename: Zhenyang
authors.initials: Z
authors.lastname: Lin
authors.forename: Guochen
authors.initials: G
authors.lastname: Jia
keywords: aromaticity; metallabenzene; metallacycles; rhenium; structure elucidation