Ionic molecular rearrangement

Photoisomerization of c/.y-stilbene 191 Ionic fragmentation reaction 191 Cyclopropyl radical ring-opening 192 Ionic molecular rearrangement 193 Ene reaction 196 Thermal denitrogenation 198 Unimolecular dissociation 199 Sn2 reaction 200... 

In summary, it should be pointed out, however, that the exact mechanism of the thermal rearrangement of sulfur rings and chains is still unknown and that further investigations are necessary in this connection. For any further discussion it may also be interesting to take into account the recent results on the molecular rearrangement reactions of cyclic selenium sulfides and of elemental selenium which take place at considerably lower temperatures compared with elemental sulfur and for which — as far as solid selenium is concerned — interesting ionic mechanisms have been proposed... 

In addition to meso-ionic examples, molecular orbital (MO) calculations have also been applied to radical work. 5-Methyl-1,3,2,4-dithiadiazolyl radical 8 has been reported to undergo a concerted rearrangement to 4-methyl-l,2,3,5-dithiazolyl radical 9 <1986CC140>. 

---