Giant ring-shaped building blocks linked to form a layered cluster network with nanosized channels: [Mo < sup > VI < /sup > < inf > 124 < /inf > Mo < sup > V < /sup > < inf > 28 < /inf > O < inf > 429 < /inf > (μ < inf > 3 < /inf > -O) < inf > 28 < /inf > H < inf > 14 < /inf > (H < inf > 2 < /inf > O) < inf > 66.5 < /inf > ] < sup > 16- < /sup >

Abstract

The synthesis of multifunctional inorganic materials from robust building blocks (synthons) that have a well-defined structure and can be linked together represents a constant challenge in crystal engineering. We report the synthesis of the deep blue mixed-valence (MoVI/MoV) compound Na16-[MorVI124MoV28O 429(μ3-O)28H14(H 2O)66.5] · ca. 300 H2O (1), which consists of nano-sized wheel-shaped building blocks with 152 Mo atoms. These discrete building blocks can be prepared easily by reduction of an acidified aqueous molybdate solution and, when linked together, they form a layered open framework with nanosized channels. The encapsulated water molecules can be partly replaced by organic molecules. The metal-oxide-based host lattice has altogether 28 4d electrons per ring. These can be assigned to 14 incomplete double-cubane-type compartments spanned by five Mo and six O atoms, which show negligible electronic interaction. The two electrons delocalized in each of these compartments give rise to the deep blue colour.