KSnI 3  ⋅ H 2 O: A New Compound with One‐Dimensional SnI 3 Chains of Pyramidal SnI 5 Polyhedra

Abstract A new compound KSnI 3 ⋅H 2 O was synthesized through the solid‐state reaction method in a sealed quartz tube. The Sn (II) cations are five‐coordinated with I − ions forming the special pyramidal SnI 5 polyhedra which further condense to one‐dimensional SnI 3 chains connected by K−I bonds and O−H⋅⋅⋅I hydrogen bonds. Meanwhile, the first principles calculations were also carried out to aid the understanding of optical properties and electronic structure. The electronic localization functions (ELF) prove the stereochemical activity of the Sn (II) lone pair and the electronic structure analysis has been carried out to understand the optical properties deeply. The calculated birefringence of the title compound is 0.121 at 1064 nm which is mainly originated from the contribution of the SnI 5 polyhedra.