Synthesis and structures of the layered vanadyl(IV) silico-germanates Li2VO(Si1−xGex)O4 (x = 0, 0.5, 1)

The synthesis and structure determination of two new members of the oxometalate family, Li2VOSiO4 and Li2VOGeO4, and one intermediate compound, Li2VO(Si0.5Ge0.5)O4, of their solid solution are presented. The structures have been determined from single-crystal X-ray diffraction. These three compounds crystallize in the tetragonal system, space group P4/nmm with a = 6.3682(6), c = 4.449(1) Å for Li2VOSiO4; a = 6.4367(4), c = 4.4929(2) Å for Li2VO(Si0.5Ge0.5)O4; and a = 6.4779(1), c = 4.520(1) Å for Li2VOGeO4. The general network, with two formulae per unit, is built up by parallel [VOXO4]n2− layers of VO5 square pyramids sharing corners with XO4 (X = Si, Ge) tetrahedra and held together by intercalated Li cations. These compounds provide the first example of layered vanadyl(IV) silicate and germanate.