Structures of the Octahedral Persulfuranes H4SF2, H2SF4, Me2SH4 and Me2SF4, and Activation Enthalpies for Their cis/trans Isomerization

✍ Scribed by Yana Steudel; Ralf Steudel

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 124 KB
• Volume: 2003
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/ejic.200300240

✦ Synopsis

Abstract

Eight hypothetical persulfurane molecules of the type X~2~SY~4~ (X, Y = H, F, Me) have been studied by ab initio MO calculations at the G3(MP2) level of theory. Depending on the substituents either the cis or the trans isomers of these octahedral molecules are most stable. While H~4~SF~2~ is most stable as the cis isomer, the global minimum structures of H~2~SF~4~, Me~2~SH~4~, and Me~2~SF~4~ are the trans isomers. The enthalpy differences between the corresponding isomers are in the range 7−53 kJ·mol^−1^. The transition states for the intramolecular cis ⇋ trans isomerization have been located in all cases. Starting from the global minimum geometries the activation enthalpies (Δ__H__^#^~298~) for this isomerization are in the range 199−263 kJ·mol^−1^, indicating rather rigid structures. Therefore, it should be possible to isolate both isomers at low to moderate temperatures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)