Reactions of 1,2-dichloroperfluorocycloalkenes and perfluorocycloalkenes with various trivalent phosphines

Fluorinated Ylides and Related Compounds

“…79,80 The early report postulated the structure as either a dipolar species which underwent rapid equilibration in solution or a nonclassic structure based on 19 F NMR data. 79 Later, Burton and co-workers were able to isolate the product and obtained a single crystal by recrystallization from a mixture of THF and ether. X-ray crystallography indicated that the product had an ylide structure in which the phosphorus-ylide carbon bond length was 1.713 Å compared with CdP of 1.665 Å and CsP of 1.828 Å, which indicated a considerable amount of double-bond character formed by the overlap of phosphorus d orbitals with the ylide carbon p orbitals (eq 78 and Table 15).…”

“…Thus, cyclic perfluoroolefins exhibited behavior similar to that of the internal perfluoroolefins. The reaction of triphenylphosphine with perfluorocyclobutene in ether at 25 °C gave a white powder, which could be isolated as crystals. , The early report postulated the structure as either a dipolar species which underwent rapid equilibration in solution or a nonclassic structure based on 19 F NMR data . Later, Burton and co-workers were able to isolate the product and obtained a single crystal by recrystallization from a mixture of THF and ether.…”

The Preparation of 1,2-Dimethylarsinohexafluorocyclopentene, 1,2-Dimethylarsinooctafluorocyclohexene, and Related Mixed Ligands

“…In general, all these reactions involving perfluorocycloolefins require more forcing conditions as the ring size is increased which is probably a consequence of ring strain (4 f,fars, and the mixed ligands fnAsP. Indeed, because of this, it is difficult to assign this band with any certainty.…”

Bis[bis(dialkylamino)phosphanyl]methanes and Bis(trifluoromethyl)acrylonitrile — Reactions and Derivatives

“…In some cases a similar migration is found for fluorine. [11,12] The forms A and B are in equilibrium with each other, and this equilibrium is usually shifted completely to the thermodynamically more stable form B. When this interconversion is separated by a high barrier, the two forms can be isolated as separate stable isomers.…”