X-ray crystal structures of K+ and Rb+ salts of [W(CN)6(bpy)]2− ion. The unusual cation–anion interactions and structure changes going from Li+ to Cs+ salts

Abstract

Complexes of the compounds K₂[W(CN)₆(bpy)]·3H₂O (1) and Rb₂[W(CN)₆(bpy)]·3.5H₂O (2) were synthesized, structurally characterized, described and compared with the lithium and cesium analogues. The salts crystallize in the triclinic (P for 1) or monoclinic (P2₁/n for 2) space group. In these salts a layered structure is observed with weak hydrophobic bpy–bpy zipper-like interactions between layers. The unexpected changes in W–W distance, thickness of layers, density and other parameters are described and discussed.