Tris(pentafluoroethyl)difluorophosphorane: A Versatile Fluoride Acceptor for Transition Metal Chemistry.

ABSTRACT: Fluoride abstraction from different types of transition metal fluoride complexes [L_n MF] (M=Ti, Ni, Cu) by the Lewis acid tris(pentafluoroethyl)difluorophosphorane (C₂ F₅ )₃ PF₂ to yield cationic transition metal complexes with the tris(pentafluoroethyl)trifluorophosphate counterion (FAP anion, [(C₂ F₅ )₃ PF₃ ]^- ) is reported. (C₂ F₅ )₃ PF₂ reacted with trans-[Ni(iPr₂ Im)₂ (Ar^F )F] (iPr₂ Im=1,3-diisopropylimidazolin-2-ylidene; Ar^F =C₆ F₅ , 1?a; 4-CF₃ -C₆ F₄ , 1?b; 4-C₆ F₅ -C₆ F₄ , 1?c) through fluoride transfer to form the complex salts trans-[Ni(iPr₂ Im)₂ (solv)(Ar^F )]FAP (2?a-c[solv]; solv=Et₂ O, CH₂ Cl₂ , THF) depending on the reaction medium. In the presence of stronger Lewis bases such as carbenes or PPh₃ , solvent coordination was suppressed and the complexes trans-[Ni(iPr₂ Im)₂ (PPh₃ )(C₆ F₅ )]FAP (trans-2?a[PPh₃ ]) and cis-[Ni(iPr₂ Im)₂ (Dipp₂ Im)(C₆ F₅ )]FAP (cis-2?a[Dipp₂ Im]) (Dipp₂ Im=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) were isolated. Fluoride abstraction from [(Dipp₂ Im)CuF] (3) in CH₂ Cl₂ or 1,2-difluorobenzene led to the isolation of [{(Dipp₂ Im)Cu}₂ ]²⁺ 2?FAP^- (4). Subsequent reaction of 4 with PPh₃ and different carbenes resulted in the complexes [(Dipp₂ Im)Cu(LB)]FAP (5?a-e, LB=Lewis base). In the presence of C₆ Me₆ , fluoride transfer afforded [(Dipp₂ Im)Cu(C₆ Me₆ )]FAP (5?f), which serves as a source of [(Dipp₂ Im)Cu)]⁺ . Fluoride abstraction of [Cp₂ TiF₂ ] (7) resulted in the formation of dinuclear [FCp₂ Ti(?-F)TiCp₂ F]FAP (8) (Cp=?⁵ -C₅ H₅ ) with one terminal fluoride ligand at each titanium atom and an additional bridging fluoride ligand.

SUBMITTER: Fohrenbacher SA 

PROVIDER: S-EPMC7898530 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature