Hypercoordinated Fluoro(pentafluoroethyl)stannanes and ‐stannates

Abstract

The treatment of phenyl-protected pentafluoroethylstannanes, Sn(C 2 F 5 ) 4-n Ph n (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 hexacoor- [a] Centrum für Molekulare Materialien,

Pentafluoroethylated Compounds of Silicon, Germanium and Tin

“…Therefore, the CO vibration mode with the highest energy represents a valuable parameter to compare the π back‐donation properties of related ligands (Table ). A direct comparison of the Si(C 2 F 5 ) 3 , Ge(C 2 F 5 ) 3 and Sn(C 2 F 5 ) 3 substituents in the related complexes [Fe(CO) 2 Cp{E(C 2 F 5 ) 3 }] and [Ni(CO) 3 {E(C 2 F 5 ) 3 }] − (E=Si, Ge, Sn) reveals only a marginally different effect of the three ligands . However, their carbonyl vibration bands are shifted by 50–128 cm −1 towards higher wavenumbers in comparison to non‐fluorinated derivatives like [Fe(CO) 2 Cp(SnBu 3 )] ( ν (CO)=1989 cm −1 ), [Fe(CO)(py)Cp(GeEt 3 )] ( ν (CO)=1960 cm −1 ) and [Fe(CO)(PEt 3 )Cp(SiEt 3 )] ( ν (CO)=1909 cm −1 )…”

“…The fluoride adducts of pentafluoroethyl‐element compounds display an extended structural diversity, which comprises penta‐ and hexacoordinated complexes as well as fluoride‐bridged dinuclear species …”

“…Whereas the [Ge(C 2 F 5 ) 3 F 3 ] 2− anion was only detected in solution in the presence of an excess of metal fluorides, eliminating benzene from phenyl‐protected stannanes with anhydrous HF affords a fluorostannane with complexed HF, [{(F 5 C 2 ) 3 SnF} 2 ⋅HF], and a whole series of octahedral fluorostannates, [Sn(C 2 F 5 ) n F 6−n ] 2− ( n= 1–4), when additional fluoride ions are provided . For the coordinatively unsaturated complexes the higher bridging tendency of tin leads to the formation of fluoride‐bridged dinuclear complexes (Scheme ) …”

“…According to the calculated FIA values (Table ) the tetrakis(pentafluoroethyl)element species are less Lewis acidic than the fluorotris(pentafluoroethyl)element derivatives but also represent valuable starting materials for the synthesis of chloride and fluoride complexes like [Si(C 2 F 5 ) 4 Cl] − and [Sn(C 2 F 5 ) 4 F 2 ] 2− …”

“…For the synthesis of transition metal complexes three applicable synthetic protocols were utilized (Scheme ) . Initially, we investigated the reaction of salts of tris(pentafluoroethyl)element anions with transition metal chlorides and carbonyl complexes like [Ni(CO) 4 ] (path I).…”