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In this contribution we present an account on pentafluoroethylated compounds of silicon, germanium and tin. The pronounced electron‐withdrawing effect of the pentafluoroethyl group leads to a markedly increased Lewis acidity at the central atom which results in the stabilization of hypervalent complexes, anionic element(II) species as well as remarkable reactivities of element‐element and element‐hydrogen bonds. By addition to unsaturated C−C bonds or by reaction with organic halides as well as transition‐metal complexes the molecules bearing a pentafluoroethyl‐element group are readily accessible. Moreover, the utilization of pentafluoroethyl groups facilitates the formation of donor‐stabilized germylenes and stannylenes. A series of such compounds serves as suitable pentafluoroethylation reagents. Conversely to the well‐studied trifluoromethyl derivatives these compounds frequently exhibit a higher thermostability, which allows a more convenient handling. The introduction of electron‐withdrawing pentafluoroethyl groups into organosilicon, organogermanium and organotin compounds creates a pronounced electron‐deficiency at the central atom, which leads to a significantly different chemical behavior with respect to non‐fluorinated derivatives. These characteristics facilitate the formation of hypervalent complexes, stabilization of low‐valent species as well as main group and transition‐metal complexes. [ABSTRACT FROM AUTHOR]

The treatment of phenyl‐protected pentafluoroethylstannanes, Sn(C2F5)4–nPhn (n = 1–3), with anhydrous HF results in the formation of the corresponding fluorostannanes which are associated in the solid state but form monomeric and dimeric fluoride complexes in solution. Due to the pronounced Lewis acidity caused by the electron‐withdrawing pentafluoroethyl groups, these stannanes represent suitable precursors for the synthesis of neutral, monoanionic and dianionic hexacoordinate tin(IV) complexes. The employment of an excess of cesium fluoride and 1,10‐phenanthroline exclusively leads to the octahedral complexes [Sn(C2F5)nF6–n]2– (n = 2–4) and [Sn(C2F5)nF4–n(phen)] (n = 1–3). The addition of bases, donating solvents as well as LiF, on the other hand, selectively affords salts containing dinuclear anions of the form [(C2F5)3Sn(µ‐F)3Sn(C2F5)3]– and [(C2F5)2F2Sn(µ‐F)2SnF2(C2F5)2]2–. [ABSTRACT FROM AUTHOR]

Syntheses of salts containing the tris(pentafluoroethyl)stannate(II) ion, [Sn(C2F5)3]−, were achieved through deprotonation of the corresponding stannane, HSn(C2F5)3, as well as by direct pentafluoroethylation of SnCl2 with LiC2F5. The electron-withdrawing substituents have substantial influence on the stability and reactivity of the anion as documented by its treatment with main group halides. Alkyl halides (R−X) underwent nucleophilic substitutions to afford RSn(C2F5)3, whereas Si, Ge, Sn, P halides gave rise to oxidation processes yielding hypervalent [SnX2(C2F5)3]− salts (X=Cl, Br, I). Moreover the unsymmetrical distannane, nBu3SnSn(C2F5)3, was disclosed as an alternative precursor for the Sn(C2F5)3 moiety. Although neither the solid state structure nor its spectra in alkane solution reveal unexpected peculiarities, unusual dissociation of the compound in coordinating solvents into [ nBu3Sn(D) n]+ and [Sn(C2F5)3]− ions was observed. [ABSTRACT FROM AUTHOR]

Owing to the highly electron-withdrawing C2F5 groups, the tris(pentafluoroethyl)germane (C2F5)3GeH represents an interesting Brønsted acidic compound. The germane is accessible by the treatment of the corresponding halogenogermanes (C2F5)3GeX (X=Cl, Br) with Bu3SnH. After clarifying its molecular structure in the solid state by X-ray diffraction, the acidity of (C2F5)3GeH was examined by treatment with different bases, for example, 1,8-bis(dimethylamino)naphthalene. The resulting germanate(II) ion [Ge(C2F5)3]− serves as a germyl group transfer reagent. The reaction with main-group and transition-metal complexes or organohalides opens access to a variety of different compounds, the structures of which were mostly determined by X-ray diffraction. The corresponding tricarbonylnickelate(0) complex [(CO)3NiGe(C2F5)3]− also gives information about the π-acceptor properties of the [Ge(C2F5)3]− ligand. Furthermore, hydrogermylation reactions of (C2F5)3GeH with alkynes afforded different stereoisomers (α,β- cis, β- trans) depending on the respective reaction conditions and substrates. [ABSTRACT FROM AUTHOR]

For (pentafluoroethyl)phenylstannanes, (C2F5)4− n SnPh n ( n=1-3), and dimethylbis(pentafluoroethyl)stannane, (C2F5)2SnMe2, a high yield synthesis was developed by the use of LiC2F5 as a C2F5 transfer reagent. The treatment of these products with gaseous hydrogen chloride or hydrogen bromide afforded (C2F5)4− nSnX n (X=Cl, Br; n=1-3) in good yields. The (pentafluoroethyl)stannanes were fully characterized by 1H, 13C, 19F and 119Sn NMR, IR spectroscopy and mass spectrometry. The treatment of the (pentafluoroethyl)tin halides (C2F5)4− nSnX n with 1,10-phenanthroline (phen) led to the formation of the corresponding octahedrally coordinated complexes [(C2F5)4− nSnX n(phen)], the structures of which were elucidated by X-ray diffraction analyses. The bromostannane (C2F5)3SnBr reacted with sodium cyclopentadienide to give the ( η 1-cyclopentadienyl)tris(pentafluoroethyl)stannane, (C2F5)3SnCp, for which single-crystal X-ray diffraction analysis could be performed. The coupling constants 1 J(119Sn,13C) and 2 J(119Sn,19F) of all new stannanes are strongly correlated and sensitive to the substitution pattern at the tin atom. For both coupling constants a negative sign could be assigned. [ABSTRACT FROM AUTHOR]

This paper gives an account on hypervalent fluoro- and chloro(pentafluoroethyl)germanium compounds. The selective synthesis of the tris(pentafluoroethyl)dichlorogermanate salt [PNP][(C2F5)3GeCl2] as well as its X-ray structural analysis is described. As a representative example for pentafluoroethylfluorogermanates, the synthesis and structure of 2,4,6-triphenylpyryliumtris(pentafluoroethyl)difluorogermanate [C23H17O][(C2F5)3GeF2] is reported. Fluoride-ion affinities for pentafluoroethylgermanes were calculated using quantum chemical methods, disclosing (C2F5)3GeF as a weaker Lewis acid than (C2F5)3SiF or (C2F5)3PF2. The theoretical results were confirmed by experiments and give the basis of a synthetic protocol for (C2F5)3GeF. Pentakis(pentafluoroethyl)germanate [PPh4][Ge(C2F5)5] was detected as an intermediate during the synthesis of [PPh4][(C2F5)4GeF] starting from tris(pentafluoroethyl)difluorogermanate and LiC2F5. [ABSTRACT FROM AUTHOR]

The chemistry of bis(pentafluoroethyl)germanes (C2F5)2GeX2 is presented. The synthesis of such species requires Br2GePh2, wherein the phenyl substituents function as suitable protecting groups. After treatment with two equivalents of LiC2F5, (C2F5)2GePh2 is produced. The replacement of the phenyl rings is smoothly effected by gaseous HBr or HCl in the presence of a Lewis acidic catalyst. The trigermoxane [(C2F5)2GeO]3 results from the reaction of (C2F5)2GeBr2 with Ag2CO3. Its crystalline 1,10-phenanthroline adduct was fully characterised by X-ray diffraction. The combination of (C2F5)2GeBr2 with Bu3SnH gave rise to the formation of (C2F5)2GeH2. [ABSTRACT FROM AUTHOR]

The synthesis of tris(pentafluoroethyl)germanium derivatives is described. The reaction of germanium tetrachloride with three equivalents of the pentafluoroethylation reagent LiC2F5 does not lead selectively to the formation of tris(pentafluoroethyl)chlorogermane, (C2F5)3GeCl. Here the introduction of a diethylamino function as a protecting group was beneficial. Thus, treatment of Cl3GeNEt2 with LiC2F5 smoothly afforded (C2F5)3GeNEt2. The replacement of the amino substituent by halides was accomplished by reaction with HBr or HCl on a multigram scale. The combination of (C2F5)3GeCl with Ag2CO3 gave rise to the formation of the digermoxane [(C2F5)3Ge]2O. An obtuse Ge-O-Ge angle of 150.2(1)° was determined by X-ray diffraction. Attempted hydrolysis of the digermoxane leads to an equilibrium mixture of the precursor, (C2F5)3GeOH, and water. [ABSTRACT FROM AUTHOR]

The introduction of electron‐withdrawing pentafluoroethyl groups into organosilicon, organogermanium and organotin compounds by the treatment of organo‐element halides with LiC2F5 creates a pronounced electron‐deficiency at the central atom with respect to non‐fluorinated derivatives. For silicon, germanium and tin reliable protocols for a cleavage of the organic protecting groups allow the synthesis of the Lewis acidic pentafluoroethyl‐element halides E(C2F5)4−nXn (E=Si, Ge, Sn; n=1–3). For a detailed discussion of this field of research see the Concept article by M. Wiesemann and B. Hoge on page 16457 ff. [ABSTRACT FROM AUTHOR]

The acidic tris(pentafluoroethyl)stannane sweetens the chemistry of tin. The reaction with the reversed polar tri‐n‐butyltin hydride afforded the highly polarized unsymmetrical distannane. In the reaction with bases, the three electron‐withdrawing pentafluoroethyl substituents stabilize the readily transferable tris(pentafluoroethyl)stannate(II) anion, a compound which should not be missed in the cocktail of basic organotin chemistry. More information can be found in the Full Paper by B. Hoge et al. on page 14476. [ABSTRACT FROM AUTHOR]

Main‐Group Chemistry The germanium awakens in the field of bis(pentafluoroethyl)germanes. Employing the phenyl group as a protecting group opens a straightforward synthetic route to (C2F5)2GePh2. To obtain functionalizable bis(pentafluoroethyl)germanes, the deprotection can be effected with gaseous HBr or HCl under the assistance of a Lewis acidic catalyst. The derivatization of the obtained halogenogermanes is described by the reactions with Ag2CO3 to obtain hexakis(pentafluoroethyl)trigermoxane and with Bu3SnH yielding (C2F5)2GeH2, studied by X‐ray diffraction. The complete story can be found in the Full Paper by B. Hoge and colleagues on page 4758 ff. [ABSTRACT FROM AUTHOR]

Arminius, without doubt Germania's liberator, is liberating a perfluorinated germanol by cleaving a digermoxane with his water sword. Both compounds represent tris(pentafluoroethyl)germanes, the general synthesis of which is described in this paper. The halogenogermanes serve as versatile starting materials for the synthesis of halogenogermanates with wide potential industrial applications, such as ionic liquids. More information can be found in the Full Paper by B. Hoge et al. on page 3327 ff. [ABSTRACT FROM AUTHOR]