An ion crystal based on silver double helicates and Keggin polyanions

An ion crystal Ag₂L₂](n-C₄H₉)₄N]PMo₁₂O₄₀] · H₂O · 0.5CH₃OH · 0.25 DMF (I) (DMF is N,N-dimethylformamide) has been synthesized by the complexation of metal double helix and Keggin polyanions in a DMF-CH₃ OH solution and structurally characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. In compound I PMo₁₂O₄₀]³⁻ anions and (n-C₄H₉)₄N]⁺ ions alternately arrange themselves in a special order in consistence with that of Ag₂L₂]²⁺ metal helicates based on π-π stacking interactions, yielding a packing of complex cations and Keggin anions.