Defluorination of perfluoroolefins by divalent lanthanoid reagents: activating carbon-fluorine bonds

Abstract

fluorine atoms from a variety of perfluoroolefins including perfluoro-2,4-dimethyl-3-ethylpent-2-ene, perfluoro-2,3-dimethylpent-2-ene, and perfluorocyclohexene. A similar abstraction of fluorine atoms from perfluorobenzene is much slower. However, visible light enhances the rate of fluorine abstraction from perfluorobenzene by MCp*2-OEt2 (M = Yb, Eu, Sm). Qualitative observation shows that the relative fluorine abstraction reactivity of the four lanthanoid complexes increases with increasingly negative reduction potential for reasonably unhindered fluoroolefin substrates. The Yb(III)/Yb(II) reduction potential of YbCp'2 solvated in acetonitrile is determined here to be -1.65 V (relative to ferrocene) by cyclic voltammetry. The fully characterized organometallic products from the fluorine atom abstraction reactions are solvated trivalent lanthanoid fluorides MCp*2F-L (M = Yb, Eu, Sm; L = diethyl ether or THF) and YbCp'2F-THF. The molecular structures of YbCp*2F-OEt2 and YbCp*2F-THF determined by X-ray crystallography reveal the first terminal lanthanoid-fluoride bonds. However, three different environments for bridging lanthanoid-fluoride bonds are seen in the X-ray determined structure of the trivalent pentaytterbium cluster [Yb5Cp*6(/u4-F)(M3-F)2(M-F)6], which is a secondary product from the further reaction of YbCp*2F with perfluoroolefins. From the X-ray data of these three trivalent ytterbium compounds the averaged Yb-F distances are 2.02 A for the terminal Yb-F bonding mode, 2.20 A for an F atom bridging between two Yb atoms, and 2.37 A for an F atom bridging between three of four Yb atoms.

Beyond Samarium Diiodide: Vistas in Reductive Chemistry Mediated by Lanthanides(II)

“…In analogy to SmI 2 , the solution synthesis of YbI 2 and EuI 2 from 1,2-diiodoethane and the corresponding metal provides straightforward access to these reagents (see Scheme 1). [6,91] Scheme 28. DyI 2 -promoted regioselective cyclotrimerization of terminal alkynes by Zhou and co-workers.…”

Bimetallic Complexes of Ytterbium and Europium Stabilized by Sterically Demanding Dipyridylamides

“…The reaction of 2 with [YbI 2 (thf) 4 ] [7] leads to the bimetallic complex 3a with a residual iodido ligand at one of the Yb atoms (Scheme 2). The molecular structure of complex 3a ( Figure 1) was investigated by X-ray crystal structure analysis (for crystallographic details please see Table 1) and NMR spectroscopy.…”

Von Ringen und Clustern: „Selbstorganisation” in der Organolanthanoidchemie

“…[11] Cp/Ln`2 mit Cp/Ln 1.2, welches sehr schön diesen Trend unterstreicht. [17] Während die ¹Cp 2 * Ybª-Einheit Teil eines 6glie-drigen Rings ist, sind die ¹Cp*Ybª-Einheiten Bausteine eines ¹Schmetterlings-Clustersª. [23] Die Klasse der Monocyclopentadienylkomplexe (Cp/Ln 1) wurde aufgrund der scheinbaren ¹sterischen Untersätti-gungª lange Zeit eher stiefmütterlich behandelt.…”