Conformational studies on seven-membered rings containing the disulfide and trisulfide groups

The Chemistry of Organic Polysulfanes R−Sn−R (n > 2)

“…In the case of 1,2,3-trithiane and other cyclic trisulfanes, the following Gibbs activation energies (kJ mol -1 ) for the ring inversion were derived: 249 For 1,2,3,4,5-pentathiepane (lenthionine 12), the Arrhenius activation energy of the ring inversion was obtained as 54 kJ mol -1 , but in addition, this sevenmembered ring undergoes pseudorotation, even at -80 °C. 250 A similar energy has been obtained for the ring inversion barrier (boat-to-boat) of a naphtho-1,2,3-trithiocin (∆H # ) 64 kJ mol -1 ). 117 However, the sterically crowded acenaphtho-acenaphthylene pentasulfane, containing a pentathiepane ring, does not undergo ring inversion at least up to 100 °C on the NMR time scale, allowing the separate preparation of the two isomers 23a and 23b (colorless crystals).…”

“…For 1,2,3,4,5-pentathiepane (lenthionine 12 ), the Arrhenius activation energy of the ring inversion was obtained as 54 kJ mol -1 , but in addition, this seven-membered ring undergoes pseudorotation, even at −80 °C . A similar energy has been obtained for the ring inversion barrier (boat-to-boat) of a naphtho-1,2,3-trithiocin (Δ H # = 64 kJ mol -1 ) .…”

Redox Convergent Synthesis and Reactivity of a Cobalt(III)‐Pentasulfido Compound

“…However, similar to the behavior of acyclic polysulfanes, the energy barriers between such isomers of cyclic polysulfanes are generally very low to allow a preparative separation [34a] . While such isomers may originate due to the ring inversion (e. g., chair and inverted chair) with Gibbs activation energies of 55–73 KJ/mol for ring inversion, other parameters such as pseudorotation (observed at RT [35] and even at −80 °C [36] ) may also be involved [19f] …”

“…[19f,34] However, similar to the behavior of acyclic polysulfanes, the energy barriers between such isomers of cyclic polysulfanes are generally very low to allow a preparative separation. [34a] While such isomers may originate due to the ring inversion (e. g., chair and inverted chair) with Gibbs activation energies of 55-73 KJ/ mol for ring inversion, other parameters such as pseudorotation (observed at RT [35] and even at À 80 °C [36] ) may also be involved. [19f] Formation of 3 from the reaction of 2 a and S 8 could have been explained simply by considering the 2-electron reduction of S 8 while the coordinated benzenethiolate and the Co(II) center would be oxidized by 1-electron each to generate Co(III) and diphenyldisulfide.…”