Routes to unique palladium A-frame complexes with a bridging fluoro-ligand

Abstract

Treatment of a toluene solution of [PdMe₂(Cy₂PCH₂PCy₂)] (1) with pentafluoropyridine in the presence of traces of water affords the generation of the A-frame complexes [(PdMe)₂{μ-κ²(P,P)Cy₂PCH₂PCy₂}₂(μ-F)][SiMeF₄] (2a) and [(PdMe)₂{μ-κ²(P,P)Cy₂PCH₂PCy₂}₂(μ-F)][OC₅NF₄] (2b). If the reaction is performed in an NMR tube equipped with a PFA inliner, complex 2b is produced, only. Treatment of 1 with pentafluoropyridine in the presence of an excess water yields the pyridyloxy complex [PdMe(OC₅NF₄)(Cy₂PCH₂PCy₂)] (3). Compound [(PdMe)₂{μ-κ²(P,P)Cy₂PCH₂PCy₂}₂(μ-F)][FHF] (2c) bearing a bifluoride anion instead of SiMeF₄⁻ or OC₅NF₄⁻ can be generated by reaction of 1 with substoichiometric amounts of Et₃N·3HF. The analogous complex [(PdMe)₂{μ-κ²(P,P)Ph₂PCH₂PPh₂}₂(μ-F)][FHF] (5c) has been synthesized by addition of Ph₂PCH₂PPh₂ to a solution of [PdMe₂(Me₂NCH₂CH₂NMe₂)] (4) in THF and subsequent treatment of the reaction mixture with Et₃N·3HF. The structure of the A-frame complex 5c has been determined by X-ray crystallography.