The Dynamic Equilibrium of Hexakis(pentafluoroethyl)distannane Adducts [XSn(C₂F₅)₃{Sn(C₂F₅)₃}]⁻ (X=Cl, Br, I, Sn(C₂F₅)₃)

Abstract

The tin-tin bond cleavage of hexaorganodistannanes by nucleophiles is a long-known reaction and widely used for stannate formation or stannyl group transfer. Herein, we detail our experiments to provide analytical evidence for the existence of the reasonably stable anionic complexes [XSn(C F ) {Sn(C F ) }] (X=Cl, Br, I, Sn(C F ) ) derived from hexakis(pentafluoroethyl)distannane. NMR investigations at low temperature lend further mechanistic insights. Thus, by detection of the imposing ion [Sn(C F ) {Sn(C F ) } ] , one can surmise that the chemistry of Sn (C F ) has more in common with the isolobal iodine than with classical distannanes.

Pentafluoroethylated Compounds of Silicon, Germanium and Tin

“…Conveniently,t he synthesis of (F 5 C 2 ) 3 SnÀSn(C 2 F 5 ) 3 does not require the isolation of Sn(C 2 F 5 ) 3 H and can also be achievedb yt he treatment of ac rude product solutiono fL i[Sn(C 2 F 5 ) 3 ]w ith gaseous HCl.T his results in the formationo ft he transientS n(C 2 F 5 ) 3 Hw hich spontaneously decomposes under liberation of H 2 . [52] The combination of three electron-donating alkyl or aryl groups with three electron-withdrawing pentafluoroethyl groups affords special structural as wella sc hemical properties of the element-element bond.…”

“…In contrast to these results the SnÀSn bond in the unpolar symmetric distannane (F 5 C 2 ) 3 SnÀSn(C 2 F 5 ) 3 does not display an exceptional reactivity. [52] However,t he six pentafluoroethyl groups result in an electron-deficiency at the tin atoms. These act, comparable to the isolobal I 2 molecule, as aL ewis acid and form elusive adducts upon the addition of appropriate nucleophiles.…”

“…[64] Anionic complexes of the form [(F 5 C 2 ) 3 SnÀ Sn(C 2 F 5 ) 3 -X] À (X = Cl, Br,I ,S n(C 2 F 5 ) 3 )a re part of ad ynamic equilibriumi ns olution. [52] Cooling decelerates these equilibria and allows ad etailed NMR spectroscopic analysiso ft hese hypervalent complexes.T hereby the tristannate anion [(F 5 C 2 ) 3 SnÀ Sn(C 2 F 5 ) 3 -Sn(C 2 F 5 ) 3 ] À ,w hich is isolobal to the well-known triiodide anion, could be investigated.…”

“…Referring to ap rotocol for the halide mediated activation of the silicon-siliconb ond in Si 2 X 6 (X = Cl, I) the addition of halides and formation of hypervalent complexes results in al ower bond order of the SnÀSn bond and concomitantly in an activation rendering the transfer of the Sn(C 2 F 5 ) 3 group to organic electrophiles. [52,65] 8. The Low-valent Bis(pentafluoroethyl)germylene Ge II (C 2 F 5 ) 2 and -stannylene Sn II (C 2 F 5 ) 2…”

“…The reaction of the corresponding stannane Sn(C 2 F 5 ) 3 H, however, with n Bu 3 SnH under these conditions invariably leads to a vigorous effervescence. The gas turned out to be dihydrogen which is liberated in an intermolecular reaction of two stannanes accompanied by the formation of the unsymmetrical distannane n Bu 3 Sn–Sn(C 2 F 5 ) 3 and the symmetrical derivative (F 5 C 2 ) 3 Sn–Sn(C 2 F 5 ) 3 . A temperature decrease to −25 °C decelerates these decomposition processes and allows the isolation of Sn(C 2 F 5 ) 3 H as the only volatile product.…”