Detlef Viets

The gas-phase structure of bis (trifluorosulfur) difluoromethane CF2(SF3)2

Abstract The gas-phase structure of CF 2 (SF 3 ) 2 has been determined by electron diffraction. The experimental intensities were fitted with a model of C 2 symmetry and the following geometric parameters ( r g distances in A and ∠ α angles in degrees with 3σ error limits) were obtained: CF=1.318 (5) A, SF eq =1.562 (6) A, SF ax =1.664 (4) A, SC=1.888 (7) A, ∠SCS=108.2 (5)°, ∠FCF=109.8 (18)°, (∠CSF ax ) mean =87.1 (3)°, ∠CSF eq =97.2 (11)°, ∠F eq SF ax =88.1 (3)° and dihedral angle δ (SCSF eq )=130.8 (9)°. The two SF 3 groups are slightly tilted away from the CF 2 group resulting in a difference between the two CSF ax angles of 4.0 (10)°. The remarkably small SCS angle of 108.2 (5)° results in a very short non-bonded contact between sulfur and one axial fluorine of the opposite SF 3 group (2.66 A) which possibly indicates the presence of an SF··S bridge.

FORMATION AND STRUCTURE OF S(O)CF2S(O)O, THE MOST SIMPLE PERFLUOROALKANE BIS(SULFINIC ACID) ANHYDRIDE

Abstract Difluoromethane bis(sulfinic acid) F 2 C(S(O)OH) 2 (3) was isolated from the hydrolysis of F 2 C(S(O)F) 2 ( 1 by moist air. Single crystals of the corresponding anhydride S(O)CF 2 S(O)O ( 2 ) were obtained after Cs′ [F 2 C(SF 3 ) 2 F] − ( 4 ) was stored in a glass vessel for several weeks. The crystal structure of 2 and preliminary results for 3 are reported.

New perfluoro-1,3-dithietane-chemistry

Abstract The BF 3 -catalysed solvolysis of SF-derivatives seems to be a general synthetic method, several other examples will be presented. Stabilities, structures, spectroscopic properties and reactivities of the compounds described will be discussed.

Die Kristallstruktur von AsF5 · / The Crystal Structure of AsF5 ·

Abstract The crystal structure of AsF5 · is reported. It crystallizes in the orthorhombic space group Pnma with a = 749.1(3) pm, b = 770.6(3) pm and c = 1630.0(5) pm, V = 960.9(6) · 106 pm3, Z = 4.

Chelation of fluoride ion by F2C(SF3)2: formation of a four-membered CS2F heterocycle with a symmetrically bridging fluoride

In the solid state CF2(SF3)2 adds F- with formation of a stable symmetrically bridged anion F2C(µ-SF3⋯)2F1–, the structure of the caesium salt of which has been determined by X-ray crystallography.

Bifunctional fluoro-sulfur-carbon-derivatives

Abstract In α,ω,-bis(trifluorosulfur)-perfluoroalkanes F 3 S(CF 2 ) n SF 3 the interesting question is the interaction of the SF 3 -groups in dependence of n. In the reaction of 1a and 1b with AsF 5 only monocations are observed, 3b forms with excess TAS-fluoride-dianions: Cations and mono-anions are fluxional in solution, preliminary X-ray-investigations on 4a show a symmetrical fluorine-bridge between the two SF 3 -groups [1]. The thermal stability of the cations strongly depends on the ring-size. 2b is indefinitely stable at room temperature, 2a decomposes already below 0°C. Structural aspects and the chemistry of the neutral specis and the ions wil be discussed.