Oxychloridoselenites( iv ) with cubane-derived anions and stepwise chlorine-to-oxygen exchange

The novel oxychloridoselenites(IV) [BMIm][Se${}_3$Cl${}_{13}$] (1), [BMIm][Se${}_4$Cl${}_{15}$O] (2), [BMIm]${}_2$[Se${}_4$Cl${}_{14}$O${}_2$] (3), [BMPyr]${}_2$[Se${}_4$Cl${}_{14}$O${}_2$] (4), [BMPyr]${}_2$[Se${}_6$Cl${}_{18}$O${}_4$] (5), [BMIm]${}_2$[SeCl${}_4$O] (6), [BMPyr]${}_2$[Se${}_2$Cl${}_6$O${}_2$] (7), and [BMPyr]${}_2$[Se${}_6$Cl${}_{14}$O${}_6$] (8) are prepared by ionic-liquid-based synthesis. Accordingly, SeCl${}_4$, SeO${}_2$ (1–6), and/or SeOCl${}_2$ (7,8) as the starting materials are reacted in [BMIm]Cl or [BMPyr]Cl as ionic liquid (BMIm: 1-butyl-3-methylimidazolium, BMPyr: 1-butyl-1-methylpyrrolidinium; partially with AlCl${}_3$ in addition). Generally, the composition and structure of title compounds can be derived from the tetrameric, heterocubane-type (SeCl${}_4$)${}_4$ as the initial building unit. Thus, chlorine is successively exchanged by oxygen from 1 to 8. Moreover, the four edge-sharing (SeCl${}_6$) octahedra in (SeCl${}_4$)${}_4$ are increasingly dismantled, ending with a [SeCl${}_4$O]${}^{2-}$ anion as a single pseudo-octahedron in 6. Based on the weakly coordinating ionic liquid, it is possible to selectively obtain the different species via synthesis near room temperature (20–80 °C). ... mehrThe oxychloridoselenite anions [Se${}_4$Cl${}_{15}$O]${}^{-}$, [Se${}_4$Cl${}_{14}$O${}_2$]${}^{2-}$, [Se${}_6$Cl${}_{18}$O${}_4$]${}^{2-}$, and [Se${}_6$Cl${}_{14}$O${}_6$]${}^{2-}$ are obtained for the first time. The title compounds are characterized by X-ray structure analysis based on single crystals and powders as well as by infrared spectroscopy and thermal analysis.