The crystal structure and absolute optical chirality of paratellurite, α-TeO2

The crystal structure of paratellurite, alpha -TeO 2 , space group P4 1 2 1 2, a=4.8082(3) AA, c=7.612(1) AA, is refined from single-crystal X-ray data (547 unique reflections). The atomic arrangement in the structure is correlated with the experimentally observed optical rotation (OR) along the unique axis. A structural origin for the OR is identified and demonstrated through the development of model structures. Calculations of the OR and birefringence in alpha -TeO 2 are made (using the program of Devarajan and Glazer) and it is demonstrated that the explicit inclusion of the contribution of the lone pair of Te(IV) to the optical response is essential for good agreement with experimental data.