The synthesis of partly fluorinated 1,3- and 1,4-dienes by palladium-catalyzed coupling makes these compounds available on the laboratory scale. Several catalyst systems were tested to maximize the yields and minimize the by-products. The molecular structures of 1,1,2,4,4-pentafluorobutadiene, chloro(N,N'-tetramethylethylenediamine)(trifluorovinyl)zinc, PCy(2)R, and P(O)Cy(2)R (Cy=cyclohexyl, R=2-(1-naphthyl)phenyl) were elucidated by X-ray crystallography.

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Now tamed: For decades preparative research on 1,1,4,4‐tetrafluorobutatriene was not pursued because of the explosive nature of the compound. Two new transition‐metal complexes containing a tetrafluorobutatriene ligand (see picture; green F/Cl, gray C, red O, purple P, orange Ir/Rh) have been prepared from the free triene, and both complexes are air‐stable.

Photochemical substitution of two carbonyl ligands of tricarbonyl(η5‐cyclopentadienyl)manganese by the butadienes, hexafluorobuta‐1,3‐diene (1a), 1,1,2,4,4‐pentafluorobuta‐1,3‐diene (1b), 1,1,4,4‐tetrafluorobuta‐1,3‐diene (1c), 1,1,2‐trifluorobuta‐1,3‐ diene (1d) und 1,1‐difluorobuta‐1,3‐diene (1e) yields the correspond‐ ing half sandwich complexes carbonyl (η4‐butadiene) (η5‐cyclopentadienyl)manganese (2a‐e), respectively. According to the IR spectrum of 2a‐e, the π acceptor strength increases with the number of fluorine atoms within the ligands 1a‐e. 2a reacts with oxygen at ambient temperature forming μ‐oxo‐bis[(cyclopentadienyl)(η1‐η1‐1,1,2,3,4,4‐hexafluorobut‐2‐en‐1,4‐diyl)manganese(IV)] (3). The structures of 2a, 2c and 3 were elucidated by X‐ray crystallography demonstrating the difference in coordination of the butadiene ligands.