Azoltrifluormethylschwefeldifluoride

Abstract

Durch Umsetzung von CF3SF3 mit den silylierten Azolen N‐Trimethylsilylpyrazol, N‐Trimethylsilylimidazol und 1‐Trimethylsilyl‐1,2,4‐Triazol wurden die entsprechenden Azoltrifluormethylschwefeldifluoride Az–SF2–CF3 in 30–40%iger Ausbeute dargestellt (Az = Pyrazol, Imidazol, 1,2,4‐Triazol). Die Struktur des Pyrazolderivats wurde durch Röntgenbeugung bestimmt.

Preparation, Characterization, and Physical Properties of Bis(imidazole)sulfur Difluoride and Bis(4-phenylimidazole)sulfur Difluoride. New Compositions with Unexpected Thermal Stability

“…The structures of compounds 2 and 4 are based on a pseudo-trigonal -bipyramidal arrangement of ligands around the central sulfur atom, with two fluorine atoms occupying axial positions and two imidazole groups and the sulfur “lone pair” in the three equatorial plane positions. The local structure around sulfur is therefore C 2 v and is in complete agreement with the expectations for AX 4 E geometry derived from VSEPR rules as well as the observed geometries in the related X-ray crystal structures of (Me 2 N) 2 SF 2 6 and (imid)SF 2 CF 3 . The planar imidazole rings in 2 are arranged around sulfur much like the blade “pitch” of a propeller, forming angles between the two ring planes and the axial F−S−F plane of 25.0° and 31.9°, respectively.…”

“…There are significant intermolecular S−N contacts in the structure of 2 (2.94 Å) which are within the sum of the van der Waals radii for S and N (3.55 Å) and which undoubtedly influence the crystal packing in this structure. A similar short contact can also be found in the structure of (imid)SF 2 CF 3 (2.859 Å) . A view of the unit cell of 2 along the c axis is given in Figure .…”

“…While this mechanism provides a satisfactory explanation of their observations in the case of unsubstituted imidazole, it cannot account for the observations in the present work, at least in the formation of 4 . If the reaction between SF 4 and 3 occurred according to the proposed mechanism of Mews and co-workers, one would expect the 5-phenyl-substituted derivative 6 to be formed via intermediate 5A as indicated in Scheme , and not compound 4 as observed in this work.

3

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“…In compound 4 , the discrepancy is even greater as the shortest intramolecular H−F distances for F(1) and F(2) are 2.110 and 2.331 Å, respectively. A similar effect presumably accounts for the nonequivalent S−F bond distances in (imid)SF 2 CF 3 2 Selected Bond Lengths (Å) and Angles (deg) for 2 , 4 , and (imid)SF 2 CF 3 7 bond or anglecompound 2 compound 4 (imid)SF 2 CF 3 7 S−F(1) 1.693(2) 1.685(3) 1.681(2) S−F(2) 1.709(2) 1.704(3) 1.717(2) S−N(1) 1.700(2) 1.706(4) 1.699(3) S−N(1‘) 1.690(3) 1.705(4) S−C(4) 1.901(4) F(1)−S−F(2) 173.86(12) 174.79(17) 171.82(11) F(1)−S−N(1) 88.71(11) 88.44(17) 88.93(11) F(1)−S−N(1‘) 88.01(11) 88.96(18) F(2)−S−N(1‘) 87.81(12) 88.01(18) F(2)−S−N(1) 87.74(12) 88.12(17) 87.89(12) N(1)−S−N(1‘) 101.74(13) 103.2(2) N(1)−S−C(4) 100.12(15) …”

7 Oxygen, sulfur, selenium and tellurium

“…Finally, a range of azole tri£uoromethylsulfurdi£uorides have been prepared in 30^40% yield. 17 Introducing heavier chalcogens into such systems has always proved something of a challenge. A signi¢cant breakthrough in this area has come with the preparation of a diselenated analogue of S 4 N 4 .…”