Kristallstrukturanalyse von 1,1,4,4-Tetrafluorbutadien und experimentelle Bestimmung der Ladungsdichte von 1,1,4,4-Tetrafluorbutatrien

Abstract

Trotz seiner hohen Instabilität gelang die Kristallzüchtung und die röntgenographische Charakterisierung des Cumulens 1,1,4,4‐Tetrafluorbutatrien, das im festen Zustand eine Fischgrätenanordnung einnimmt (siehe Bild). Aus experimentellen und berechneten Ladungsdichteverteilungen ergibt sich erwartungsgemäß, dass die zentrale Doppelbindung kürzer ist und eine höhere Ladungsdichte aufweist als die beiden äußeren Bindungen.

Organometallic chemistry of fluorinated propadienes and butadienes

“…The early synthesis of 1,1,4,4-tetrafluorobuta-1,3-diene by radical addition of 1-iodo-2,2-difluoroethene to 1,1,-difluoroethene followed by elimination of hydrogen iodide gives only low yields of the dien [36]. Using palladium catalyzed C-C coupling reactions [37], an effective synthesis of 1,1-difluorobuta-1,3-diene [38], 1,1,4,4-tetrafluorobuta-1,3-diene [38], pentafluorobuta-1,3-diene [38] and hexafluorobutadiene [38] could be developed using 2,2-difluoro-1-iodoethene and bromotrifluoroethene, respectively, via the zinc [39] and tin [40] compounds, respectively. 1,1,2-Trifluorobuta-1,3-diene was prepared by dihydrohalogenation of commercially available 1,1,2-trifluoro-4-bromo-but-1-ene [41].…”

“…8) [38] and octafluoro-1,2-dimethylenecyclobutane [32] were determined by X-ray crystallography at low temperature allowing a comparison of their structural data with that of metal complexes.…”

“…Addition of bromine onto 1,1,4,4-tetrafluorobuta-1,3-dien gives the 1,4-dibromo compound 27 [38,46]. The dehydrohalogenation of 27 by potassium hydroxide yields tetrafluorobutatrien 28 (Scheme 10) [38,46].…”

“…The dehydrohalogenation of 27 by potassium hydroxide yields tetrafluorobutatrien 28 (Scheme 10) [38,46]. The molecular structure and an experimental charge density determination of 28 were obtained by X-ray diffraction at 100 K [38].…”

“…The dehydrohalogenation of 27 by potassium hydroxide yields tetrafluorobutatrien 28 (Scheme 10) [38,46]. The molecular structure and an experimental charge density determination of 28 were obtained by X-ray diffraction at 100 K [38]. Very recently, Hughes et al succeeded in preparing the first tetrafluorobutatrien complex, Cp*Ir(PMe 3 )(Z 2 -C 4 F 4 ) by reduction of Cp*Ir(PMe 3 )(I){CF(CF 3 )(C 2 F 5 )} with NaC 10 H 8 [47].…”