Die Kristallstruktur des SF₅⁻‐Anions

Abstract

Das Carbanion SF5C(CF3)2− zersetzt sich langsam zu SF5− und (CF3)2CC(CF3)2. Die Pentafluorosulfate(IV) wachsen dabei in großen Kristallen, die in Gegenwart eines SF4‐Gasdruckes längere Zeit haltbar sind. Die Kristallstrukturanalyse des Rb+SF5− (Pbnm, a = 776,1(14), b = 990,3(5), c = 614,1(3) pm, Z = 4) zeigt das SF5−‐Anion in seiner erwarteten quadratisch‐pyramidalen Struktur. Die axiale Bindung ist beträchtliche 15,9 pm kürzer als die durchschnittliche äquatoriale SF‐Bindung. Auch befindet sich der Schwefel deutlich unterhalb der Ebene, die durch die vier äquatorialen Fluoratome gebildet wird. Vom reinen Cs+SF5− konnten bisher nur Zwillingskristalle erhalten werden. Durch Zufall gelang die Isolierung eines Doppelsalzes (Cs+)6(SF5−)4 (HF2−)2. Die Kristallstrukturanalyse (P4b2, a = 1031,7(15), c = 627,6(9) pm, Z = 1), zeigt das Vorhandensein der gleichen SF5‐Struktureinheiten wie im Rb+SF5−.

Nucleophilic Activation of Sulfur Hexafluoride: Metal‐Free, Selective Degradation by Phosphines

“…Similar metric parameters have been observed in reported compounds containing the SF 5 − anion: Rb + [SF 5 − ], Cs + 6 [SF 5 − ] 4 [HF 2 − ] 2 , [Cs(18‐crown‐6) 2 + ][SF 5 − ], and [HNC 5 H 3 (CH 3 ) 2 + ] 2 F − [SF 5 − ]⋅4 SF 4 . In contrast to the reported salts containing the SF 5 − anion, 3 a is thermally stable up to 140 °C and can be stored under an atmosphere of dry argon for months.…”

Reactions of the “Naked” Fluoride Ion: Syntheses and Structures of SeF and BrF

“…These pentafluorochalcogenates(1v) have a square-pyramidal structure and have been investigated very thoroughly. [14] Occasional reports of the existence of hexafluorochalcogenates have not been substantiated." '] The fact that these anions were seemingly nonexistent was interpreted in terms of a duodecet rule, that is, by assuming that nonmetal elements of the second and third row of the periodic table can accommodate only 12 electrons in their valence shell, and only elements of the fourth row are able to accommodate more (IF,, XeF,, XeFi -).…”

Lewis Acid Behavior of SF4: Synthesis, Characterization, and Computational Study of Adducts of SF4with Pyridine and Pyridine Derivatives

“…[4] Extensive overlapo ft he IR bands of product and reactantp recluded definitive identification. In contrast, conclusive evidencef or the Lewis acid behavior of SF 4 towards fluoridei ons has been established by the synthesis of [N(CH 3 ) 4 ] [SF 5 ], [5] Cs [SF 5 ], [6] Rb [SF 5 ], [7] [((CH 3 ) 2 N) 3 5 ], [8] and [Cs(18crown-6) 2 ][SF 5 ]. [9] The crystal structures of Rb[SF 5 ], [7] Cs 6 [SF 5 ] 4 [HF 2 ] 2 , [7] [Cs(18-crown-6) 2 ][SF 5 ], [9] and [HNC 5 H 3 -(CH 3 ) 2 ] 2 F···SF 4 [SF 5 ]·3SF 4 [10] have confirmed the expected square pyramidal geometry of the [SF 5 ] À anion.…”