Spontaneous Resolution upon Crystallization of 3D, Chiral Inorganic Networks Assembled from Achiral, Polyoxometallate Units and Metal Ions

Two enantiomerically pure 3D chiral POM-based compounds <b>1a</b> and <b>1b</b>, having formula (H₃O⁺)₂[K₂(SiW₁₂O₄₀)­(H₂O)₄]·H₂O, have been isolated during crystallization. Single-crystal X-ray diffraction analysis revealed that <b>1a</b> and <b>1b</b> are enantiomers, crystallizing in chiral space groups <i>P</i>6₂22 and <i>P</i>6₄22, respectively. The compounds are optically active, and their UV spectra show Cotton effects in the opposite direction. Compounds <b>1a</b> and <b>1b</b> represent the examples of 3D chiral frameworks of POM-based inorganic skeletons, obtained by spontaneous resolution upon crystallization from achiral precursors. The crystal structures represent open frameworks with water molecules in the chiral, nanotubular channels