2-DIMENSIONAL POLYTYPISM OF CRYSTALLINE (C(5)ME(5))REO3

Crystals of CpReO3 present a rare case of two-dimensional polytypism. They consist of a polytypic packing (in the bc plane) of ordered pola r chains of three-legged piano-stool CpReO3 molecules (stacked head-t o-tail along the a axis). The two-dimensional polytypism arises from t he 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 .