Syntheses of highly unsaturated isocyanidesvia organometallic pathways

Abstract

The carbon carbon coupling reaction by nucleophilic attack of (CO)₅Cr(CN–CFCF₂) 1 by lithium or Grignard compounds 2a–i yields the isocyanide complexes (CO)₅Cr(CN–CFCF–R) 3a–i (a R = CHCH₂, b R = CHCF₂, c R = CCH, d R = CC–SiMe₃, e R = CC–Ph, f R = CC–C₆F₄OMe, g R = CC–C₆H₃(CF₃)₂, h R = C₆F₅, i R = C₆H₃(CF₃)₂) as mixtures of E and Z isomers. The dinuclear complexes 5a–c are obtained from the reaction of 1 with the dilithio or dimagnesium compound 4a–c as the Z,Z-, E,Z- and E,E-isomers, respectively. (CO)₅Cr(CN–CFCF–CC–CC–CFCF–NC)Cr(CO)₅7 is obtained as a mixture of Z,Z-, Z,E- and E,E-isomers from (CO)₅Cr(CN–CFCF–CC–H 3d by Eglington-Glaser coupling. (CO)₅Cr(CN–CFCF–CC–CFCF–NC)Cr(CO)₅6 and (CO)₅Cr(CN–CFCF–CC–CC–CFCF–NC)Cr(CO)₅7 react with octacarbonyldicobalt forming the cluster compounds Z,Z-[{η²-μ₂-(CO)₅Cr(CN–CFCF–CC–CFCF–NC)Cr(CO)₅}Co₂(CO)₆] Z,Z-8, E,Z-[{η²-μ₂-(CO)₅Cr(CN–CFCF–CC–CFCF–NC)Cr(CO)₅}Co₂(CO)₆] E,Z-8 and E,E-[{η²-μ₂-(CO)₅Cr(CN–CFCF–CC–CFCF–NC)Cr(CO)₅}Co₂(CO)₆] E,E-8 and Z,Z-[{η²-μ₂-(CO)₅Cr(CN–CFCF–CC–CC–CFCF–NC)Cr(CO)₅}{Co₂(CO)₆}₂] Z,Z-9, E,Z-[{η²-μ₂-(CO)₅Cr(CN–CFCF–CC–CC–CFCF–NC)Cr(CO)₅}{Co₂(CO)₆}₂] E,Z-9 and E,E-[{η²-μ₂-(CO)₅Cr(CN–CFCF–CC–CC–CFCF–NC)Cr(CO)₅}{Co₂(CO)₆}₂] Z,Z-9, respectively. The crystal and molecular structures of E-3d, Z-3h, Z,Z-8, E,Z-8 and Z,Z-9 were elucidated by single-crystal X-ray crystallography.