Solid-state reactions between SiI₄ (or GeI₄) and Li₂(CN₂) pass through amorphous stages to finally yield the unprecedented Li₄[Si(CN₂)₄] (or Li₄[Ge(CN₂)₄]). Tetracyanamidometallate anions may be combined with various cations of the PSE.

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.