Two-dimensional polytypism of "crystalline" (C5Me5)ReO3

Crystals of Cp*ReO3 present a rare case of two-dimensional polytypism. They consist of a polytypic packing (in the bc plane) of ordered polar chains of three-legged piano-stool Cp*ReO3 molecules (stacked head-to-tail along the a axis). The two-dimensional polytypism arises from the possibility of building a similar motif both with 2-fold screw axes and inversion centers as packing operators, i.e. from the possibility of packing together neighboring chains of equal or different polarity.