Abstract: | The crystal structures of two new oxides, BiReO4 and BiRe2O6, have been determined by single-crystal X-ray methods using an Enraf-Nonius CAD-4F diffractometer. BiReO4 crystallizes as red metallic needles in the space group Cmcm, cell dimensions a = 3.839(1) Å, b = 14.914(2) Å, c = 5.534(1) Å, Z = 4. The structure consists of sheets of corner-shared octahedra (composition ReO4) linked by Bi atoms (R = 2.55%). BiRe2O6 crystallizes as black metallic plates in the space group C2/m, cell dimensions a = 5.516(1) Å, b = 4.906(1) Å, c = 8.384(1) Å, β = 106.71(1)°, Z =2. The structure consists of layers containing Re2O10 units linked together by corner sharing of the octahedra, alternating with layers of Bi atoms (R = 2.61%). The structure is disordered due to the random stacking of the Re layers. The Re---Re distance of 2.5 Å in the Re2O10 unit is comparable to that found in similar compounds. Both compounds exhibit stereochemically active lone pairs. |