Structural chemistry of vanadium oxides with open frameworks

The present work is dedicated to a crystal-chemical and topographical analysis of vanadium oxides with open structures. The review covers, apart from a few exceptions, only pure vanadium oxide structures with vanadium in oxidation states greater than +3. Purely tetrahedral frameworks are not discussed because of their traditional, well known crystal chemistry and only a few examples of cluster compounds are provided. Structural classification and notation of vanadium oxide frameworks are proposed based on the following scheme: polyhedra → chain → layer → three-dimensional framework. Thus, approximately 60 types of vanadium oxide frameworks are divided into five classes by type of coordination polyhedra present and into 14 subclasses by a more complex structural formation. Details are also given of the analysis of vanadium–oxygen coordination polyhedra and their metamorphosis: tetrahedron–trigonal bipyramid–square pyr­amid–octahedron, as well as the combinatorial deduction of possible structures for the most common framework types.