Co-crystallization of octahedral and icosahedral fluoroanions in K3(AsF6)(B12F12) and Cs3(AsF6)(B12F12). Rare examples of salts containing fluoroanions with different shapes and charges

Crystals grown from anhydrous HF solutions of CsAsF6 and Cs2B12F12 or KAsF6 and Cs2B12F12 are shown by Raman spectroscopy and single-crystal X-ray diffraction to be the ternary salts K3(AsF6)(B12F12) or Cs3(AsF6)(B12F12). Both compounds exhibit a modified version of the anti-perovskite structure. They are rare examples of crystals that simultaneously contain octahedral and icosahedral molecular species and are also rare examples of salts containing fluoroanions with different shapes and charges. The crystallographic results show that both compounds are densely packed.