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

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.

Stepwise addition of difluorocarbene to a transition metal centre.

The Ruppert-Prakash reagent (Me3SiCF3) is used to introduce difluorocarbene (CF2) and tetrafluoroethylene (TFE) ligands to cobalt(I) metal centres, whereby the TFE ligand is generated via [2+1] cycloaddition between [Co]=CF2 and CF2.

Cobalt fluorocarbenes: cycloaddition reactions with tetrafluoroethylene and reactivity of the perfluorometallacyclic products.

Cobalt fluorocarbene complexes CpCo(═CFR(F))(PPh2Me) (Cp = η(5)-C5H5, R(F) = F or CF3) react with tetrafluoroethylene to give the metallacyclobutanes CpCo(κ(2)-CFR(F)CF2CF2-)(PPh2Me) in the first examples of cycloaddition reactions between perfluoroalkenes and metal perfluorocarbenes. The metallacyclic products undergo a variety of reactions upon activation of the C-F bonds, including Brønsted acid-catalyzed C-F/Co-C scrambling. Implications for metal-catalyzed metathesis and polymerization of perfluoroalkenes are discussed.

Metal-free borylative ring-opening of vinyl epoxides and aziridines.

A rational approach towards the borylative ring-opening of vinylepoxides and vinylaziridines, by the in situ formed MeO(-)→bis(pinacolato)diboron adduct, has been developed. The enhanced nucleophilic character of the Bpin (sp(2)) moiety from the reagent favours the SN2' conjugated B addition with the concomitant opening of the epoxide and aziridine rings. The reaction proceeds with total chemoselectivity towards the polyfunctionalised (-OH or -NHTs) allyl boronate.