Metathesis and Metallacycle Reactivity of d10 Ni Perfluorocarbenes with Alkenes

• Published in: Organometallics 2024-06, Vol.43 (11), p.1213-1221
• Main Authors: Daniels, Alex L., Ghaffari, Behnaz, Kong, Deqing, Guan, Jia, Hall, Michael B., Baker, R. Tom
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/acs.organomet.4c00026

We showed previously that the d10 nickel perfluorocarbene complex, P3NiCF­(CF3) [P = P­(O i Pr)3], 1, reacts with fluoroalkenes to produce both 4-membered nickelacycles and metathesis products via separate reaction pathways. Herein, we compare the reactivity of 1 with a variety of alkenes. The reaction of 1 with hexafluoropropene [CF2CF­(CF3), HFP] affords a single metallacycle, taking advantage of the diradical mechanism in which the carbene carbon adds to the CF2 end of HFP. In contrast, 1 and perfluoro­(methyl vinyl ether), CF2CF­(OCF3), yield both metallacycle and metathesis products, with preferential formation of the more stabilized difluorocarbene [P3NiCF2 vs P3NiCF­(OCF3)] and a higher ratio of metathesis to metallacycle products than using tetrafluoroethylene or vinylidene difluoride. Attempts to form fluoropolymers via ring-opening metathesis polymerization of perfluorocyclobutene and hexafluorocyclopentene briefly gave new nickel carbenes but then yielded Ni fluoroalkene complexes with the loss of the CF­(CF3) unit. Surprisingly, both ethylene and styrene derivatives gave only metallacycles, although evidence was obtained for alkene coordination to nickel; computational studies are presented to identify the origin of these observations. Finally, insertion of ethylene into the ethylene-derived nickelacyclobutane afforded a new fluorinated alkene, CH2CHCH2CH2CHFCF3, formed presumably via nickelacyclohexane through selective β-H and reductive eliminations.