The versatility of lithium cation coordination modes in salts with [W(CN)6(bpy)]2− anions

Abstract

The synthesis and spectral and structural descriptions of two salts of formulas {[Li][Li(H₂O)(μ-CN)₃]}[W(CN)₃(bpy)] (1) and {Li}{[Li(μ-CN)₂][Li(μ-CN)₃]μ-Cl}[W(CN)(bpy)]·2H₂O (2) were described. The structural investigation shows the influence of the size and charge of Li⁺ on the nature of the CN⁻/Li⁺ interaction and thus on the structure of the compounds. Both salts crystallize in the triclinic P space group with very similar cell parameters (a, b and c differ by no more than 0.05 Å, α, β and γ less than 1°, and cell volume less than 4 ų) in spite of the different complex formulas. In 1, two different lithium cations are observed. Only one compensates the anion charge, while the second one is tetrahedral and forms a complicated 1D network via three nitrogen atoms of cyano ligands trans to a bpy molecule. The molecular wires connect neighbouring molecules only by weak intermolecular interactions. In 2, the 2D structure, with layers connected only by π–π stacking interactions, is observed. Lithium cations are involved in bonds with the nitrogen of cyano ligands.