title: A stable germanone as the first isolated heavy ketone with a terminal oxygen atom.
abstract: The carbon-oxygen double bond of ketones (R(2)C=O) makes them among the most important organic compounds, but their homologues, heavy ketones with an E=O double bond (E = Si, Ge, Sn or Pb), had not been isolated as stable compounds. Their unavailability as monomeric molecules is ascribed to their high tendency for intermolecular oligomerization or polymerization via opening of the E=O double bond. Can such an intermolecular process be inhibited by bulky protecting groups? We now report that it can, with the first isolation of a monomeric germanium ketone analogue (Eind)(2)Ge=O (Eind = 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl), stabilized by appropriately designed bulky Eind groups, with a planar tricoordinate germanium atom. Computational studies and chemical reactions suggest the Ge=O double bond is highly polarized with a contribution of a charge-separated form (Eind)(2)Ge(+)-O(-). The germanone thus exhibits unique reactivities that are not observed with ordinary ketones, including the spontaneous trapping of CO(2) gas to provide a cyclic addition product.
authors.affiliation: Functional Elemento-Organic Chemistry Unit, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Liangchun
authors.initials: L
authors.lastname: Li
authors.forename: Tomohide
authors.initials: T
authors.lastname: Fukawa
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Matsuo
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hashizume
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fueno
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Tanaka
authors.forename: Kohei
authors.initials: K
authors.lastname: Tamao
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry; D004583:Electrons; D005857:Germanium / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D058105:Polymerization
chemical_list: D007659:Ketones; D005857:Germanium; D002245:Carbon Dioxide