Tuning the Structures of AsMo12 and AsW12 into Chiral Crystals by Introducing CH3CN and H2O

Abstract. The asymmetrical crystal [Na(15C5)2][Na(15C5)]2(AsMo12O40)]·CH3CN (1) was synthesized. Interestingly, the huge α-keggin ion AsMo12 is distorted by introduction of CH3CN molecules and adopts a chiral assembly with space group P4. In contrast, the analogous compound AsW12 co-crystallizes with trace H2O molecules. The hydrogen atoms of H2O are positionally disordered with 50 % occupation to correlate with AsW12 in space group P4/m. Solid and solution CD spectra indicate that the crystals of 1 are in R configuration. This leads to the conclusion that molybdenum has greater affinity toward organic CH3CN, whereas tungsten has greater affinity to inorganic H2O. Additionally, AsMo12 shows greater deformability than AsW12. It is suggested that POMo shows a greater potential as chiral material than POW because of the flexibility of Mo. As a highlight, CH3CN can function as a general chiral inducer for the innovation of other chiral crystals, if fixed along one dimension.