Solvent- and anion-dependent rearrangement of fluorinated carbene ligands provides access to fluorinated alkenes.

The construction of fluorocarbene ligands within the coordination sphere of transition metal complexes using sequential nucleophilic and electrophilic addition to a vinylidene complex is described. Reaction of [Ru(η5-C5H5)(dppe)([double bond, length as m-dash]C[double bond, length as m-dash]CPhF)][N(SO2Ph)2] with [NMe4]F results in nucleophilic attack of fluoride at the metal-bound carbon of the vinylidene ligand to give alkenyl complex [Ru(η5-C5H5)(dppe)(-CF[double bond, length as m-dash]CFPh)]. Subsequent eletrophilic fluorination with N-fluorobenzenesulfonimide (NFSI) results in the formation of the fluorinated carbene complex [Ru(η5-C5H5)(dppe)([double bond, length as m-dash]CF-CHFPh)][N(SO2Ph)2]. The fluorocarbene complexes undergo rearrangement to liberate free fluorinated alkenes, a process governed by the choice of solvent and anion, representing a new metal-mediated route to fluorinated alkenes from alkynes.