Inorganic Complexes including the rock-salt structure
Edge sharings of MO6 octahedra may give a cluster structure that exhibit a regular array of cations and anions resembling a structural part of the NaCl packing. For example, a M6 core is known as a Lindqvist structure. An arrangement of six MO6 octahedra produces an even larger octahedron. In vanadium chemistry, the build-up cahrges on [V6O19]8- unit are too big, and does not allow the formation of the M6 core, which is popular in molybdates and tungstates. Substitution of oxido group to alkoxo group reduces the charge build-up and the hexavanadate cores are available in alkoxo derivatives. A V10 type complex is called decavanadates and it is the most representative polyoxovanadates. A V17 type structure has the 3x3x3 core similar to the NaCl unit cell, that is often shown in chemistry textbook. In another view, the face sharings of eight cubes by V4O4 units produces even larger cube, that is called as a super-cubane framework.
