Alex L. Daniels, Behnaz Ghaffari, Deqing Kong, Jia Guan, Michael B. Hall* and R. Tom Baker*,
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引用次数: 0
Abstract
We showed previously that the d10 nickel perfluorocarbene complex, P3Ni═CF(CF3) [P = P(OiPr)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.
期刊介绍:
Organometallics is the flagship journal of organometallic chemistry and records progress in one of the most active fields of science, bridging organic and inorganic chemistry. The journal publishes Articles, Communications, Reviews, and Tutorials (instructional overviews) that depict research on the synthesis, structure, bonding, chemical reactivity, and reaction mechanisms for a variety of applications, including catalyst design and catalytic processes; main-group, transition-metal, and lanthanide and actinide metal chemistry; synthetic aspects of polymer science and materials science; and bioorganometallic chemistry.