The Tris(pentafluoroethyl)stannate(II) Anion, [Sn(C2F5)3]−-Synthesis and Reactivity

Repurposing of F-gases: challenges and opportunities in fluorine chemistry

Fluorinated gases (F-gases) are routinely employed as refrigerants, blowing agents, and electrical insulators. These volatile compounds are potent greenhouse gases and consequently their release to the environment creates a significant contribution to global warming. This review article seeks to summarise: (i) the current applications of F-gases, (ii) the environmental issues caused by F-gases, (iii) current methods of destruction of F-gases and (iv) recent work in the field towards the chemical repurposing of F-gases. There is a great opportunity to tackle the environmental and sustainability issues created by F-gases by developing reactions that repurpose these molecules.

A Zwitterionic Phosphonium Stannate(II) via Hydrogen Splitting by a Sn/P Frustrated Lewis-Pair and Reductive Elimination

The reactivity of the frustrated Lewis pair (FLP) (F₅C₂)₃SnCH₂P(tBu)₂ (1) was investigated with respect to the activation of elemental hydrogen. The reaction of 1 at elevated hydrogen pressure afforded the intramolecular phosphonium stannate(II) (F₅C₂)₂SnCH₂PH(tBu)₂ (3). It was characterized by means of multinuclear NMR spectroscopy and single crystal X‐ray diffraction. NMR experiments with the two isotopologues H₂ and D₂ showed it to be formed via an H₂ adduct (F₅C₂)₃HSnCH₂PH(tBu)₂ (2) and the subsequent formal reductive elimination of pentafluoroethane; this is supported by DFT calculations. Parahydrogen‐induced polarization experiments revealed the formation of a second product of the reaction of 1 with H₂, [HP(tBu)₂Me][Sn(C₂F₅)₃] (4), in ¹H NMR spectra, whereas 2 was not detected due to its transient nature.

Pentafluoroethylated Compounds of Silicon, Germanium and Tin

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 Dynamic Equilibrium of Hexakis(pentafluoroethyl)distannane Adducts [XSn(C2 F5 )3 {Sn(C2 F5 )3 }]- (X=Cl, Br, I, Sn(C2 F5 )3 )

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(C₂ F₅ )₃ {Sn(C₂ F₅ )₃ }]^- (X=Cl, Br, I, Sn(C₂ F₅ )₃ ) derived from hexakis(pentafluoroethyl)distannane. NMR investigations at low temperature lend further mechanistic insights. Thus, by detection of the imposing ion [Sn(C₂ F₅ )₃ {Sn(C₂ F₅ )₃ }₂ ]^- , one can surmise that the chemistry of Sn₂ (C₂ F₅ )₆ has more in common with the isolobal iodine than with classical distannanes.