d¹⁰ Nickel Difluorocarbenes and Their Cycloaddition Reactions with Tetrafluoroethylene

Abstract

We report the first isolable nickel difluorocarbene complexes (NiP 2 [P(OMe) 3 ](═CF 2 ); P 2 = Ph 2 P(CH 2 ) 2 PPh 2, 2 P(OMe) 3 ), which are also the only examples of formally d 10 metal fluorocarbenes. These [Ni 0 ]═CF 2 complexes react with tetrafluoroethylene (TFE) to yield the rare perfluorometallacyclobutanes [NiP 2 (κ 2 -CF 2 CF 2 CF 2 −)], with potential relevance to fluoroalkene metathesis and polymerization. Preliminary kinetic experiments establish that the reactions of the new [Ni]═CF 2 compounds with TFE are considerably faster than the analogous reactions of their previously reported [Co]═CF 2 counterparts. Further, we show that TFE addition to 2 is a dissociative process, in contrast to [Co]═CF 2, which reacts with TFE in an associative fashion. Finally, the preliminary reactivity of NiP 2 (κ 2 -CF 2 CF 2 CF 2 −) (P 2 = Ph 2 P(CH 2 ) 2 PPh 2 ) is described.