Perfluoroalkyl Cobalt(III) Fluoride and Bis(perfluoroalkyl) Complexes: Catalytic Fluorination and Selective Difluorocarbene Formation

Abstract

Four perfluoroalkyl cobalt(III) fluoride complexes have been synthesized and characterized by elemental analysis, multinuclear NMR spectroscopy, X-ray crystallography, and powder X-ray diffraction. The remarkable cobalt fluoride (19)F NMR chemical shifts (-716 to -759 ppm) were studied computationally, and the contributing paramagnetic and diamagnetic factors were extracted. Additionally, the complexes were shown to be active in the catalytic fluorination of p-toluoyl chloride. Furthermore, two examples of cobalt(III) bis(perfluoroalkyl)complexes were synthesized and their reactivity studied. Interestingly, abstraction of a fluoride ion from these complexes led to selective formation of cobalt difluorocarbene complexes derived from the trifluoromethyl ligand. These electrophilic difluorocarbenes were shown to undergo insertion into the remaining perfluoroalkyl fragment, demonstrating the elongation of a perfluoroalkyl chain arising from a difluorocarbene insertion on a cobalt metal center. The reactions of both the fluoride and bis(perfluoroalkyl) complexes provide insight into the potential catalytic applications of these model systems to form small fluorinated molecules as well as fluoropolymers.

Fluorocarbene, fluoroolefin, and fluorocarbyne complexes of Rh

“…8 Baker has also shown that cationic cobalt( iii ) difluorocarbenes could undergo migratory insertion into perfluoroalkyl ligands, possibly providing a blueprint for transition metal catalyzed perfluoroolefin polymerization. 9 …”

Acyl Fluorides in Late‐Transition‐Metal Catalysis

“…A catalytic variant of such a substitution was reported by Baker and co‐workers in 2015 . An acyl fluoride was generated quantitatively in the presence of CpCo(CF 3 )(F)(PPh 2 Me) as the catalyst when AgF was employed as the fluoride source.…”

Carbonsäurefluoride in der Katalyse durch späte Übergangsmetalle

“…Eine katalytische Version der Substitution wurde 2015 von Baker et al. beschrieben . Hierbei wurde ein Carbonsäurefluorid quantitativ von CpCo(CF 3 )(F)(PPh 2 Me) als Katalysator mit AgF als Fluoridquelle generiert.…”