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.