Synthesis, Structure, and Electronic Properties of Sn(CN2) and Sn4Cl2(CN2)3.

A solid-state metathesis reaction between equimolar amounts of Li2(CN2) and SnCl2 revealed the formation of two new compounds, Sn4Cl2(CN2)3 and Sn(CN2). Thermal analysis of this reaction indicated that Sn4Cl2(CN2)3 forms exothermically near 200 °C and subsequently transforms into Sn(CN2) at higher temperatures. The crystal structures of both compounds are presented. According to optical measurements and band structure calculations, Sn(CN2) can be considered as a semiconductor with a band gap on the order of 2 eV. The presence of Sn2+ ions in the structure of Sn(CN2) with a toroidally shaped lone pair is indicated by electron localization function calculations. The structure of Sn(CN2) is shown to be related to the structures of FeS2 and CaC2.