Crystallization of the Fundamental Tetracyanamidometallates Li₄[Si(CN₂)₄] and Li₄[Ge(CN₂)₄] from Polymeric Li‐T‐(NCN)‐I Precursors (T=Si, Ge)

Abstract

The tetracyanamidometallates Li4[T(CN2)4] with T=Si, Ge were prepared by solid‐state metathesis (SSM) reactions between TI4 and Li2(CN2). The new compounds Li4[T(CN2)4] are obtained as crystalline phases in high yields and represent the most basic examples of the family of tetracyanamidometallates. The formation of these compounds, via SiI4 and Li2(CN2), is analyzed by means of differential scanning calorimetry (DSC). The [Si(CN2)4]4− ion in the structure of Li4[Si(CN2)4] can be considered an analogue to the [SiO4]4− ion in Li4SiO4. The crystal structures of Li4[T(CN2)4] were solved and refined isotypically on the basis of single‐crystal X‐ray diffraction data in the space group C2/c, and further characterized by infrared and solid‐state NMR techniques.