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.