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.

A Monoanionic Arsenide Source: Decarbonylation of the 2‐Arsaethynolate Anion upon Reaction with Bulky Stannylenes

“…The molecular structure of the minor component 4 shows a Sn−As distance of 2.425(17) Å, which is in reasonable agreement with the value computed for an isolated anion of 2.375 Å. Compound 4 is isoelectronic with a family of R 2 Sn=X (X=S, Se, Te) compounds previously reported in the literature 48, 49, 50. The ratio of both compounds was found to vary with subsequent data collections on the same crystal so that we assume that photolytic decarbonylation is caused by X‐ray irradiation; however, because of the crystal decomposition, no complete decarbonylation could be achieved in the X‐ray beam.…”

Synthesis and Structures of Sterically Congested Diarylsilanes Bearing Two Bulky Rind Groups

“…3 The germanone was obtained by the treatment of a germylene, (Eind) 2 Ge:, with trimethylamine N-oxide as an oxygen source. Practically, the precursor, two-coordinate Ge(II) species, (Eind) 2 Ge:, can readily be prepared by the reaction of a commercially available dichlorogermylene dioxane complex, GeCl 2 ¢dioxane, with 2 equiv of the bulky aryllithium, (Eind)Li.…”

“…Following the successful achievement of the monomeric germanone via the stable germylene with the two bulky Eind groups, 3 we have been interested in extending this chemistry to silicon species. However, it appears to be rather difficult to introduce two bulky substituents on the silicon atom, 4 which is mainly due to the smaller covalent atomic radius of silicon and the unavailability of general dihalosilylene reagents.…”

“…The Rind-substituted trihydrosilanes, (Rind)SiH 3 (1), 9 can be conveniently obtained by the reactions of (Rind)Li with (EtO) 3 SiH followed by reduction with lithium aluminum hydride (LAH) in good yields.…”

Fused-Ring Bulky “Rind” Groups Producing New Possibilities in Elemento-Organic Chemistry

“…In 2012, we reported the first isolation of a monomeric germanone, (Eind) 2 Ge=O (19), with the planar tricoordinate germanium atom and a terminal oxygen atom, protected by the two bulky Eind groups (Scheme 10). 33 Chemical reactions and computational studies indicate that the Ge=O double bond is highly polarized with a contribution of a charge-separated form, germylene oxide, (Eind) 2 Ge…”