Vanadate-phosphate ring

The aqueous solutions of the glasses with P/V ratios of 2-10 contain predominant amounts of diphosphate in comparison with the other short-chain phosphates. From this fact it seems probable that vanadate-phosphate rings are also present in the glasses. 

Two-dimensional and three-dimensional structures containing analogous and related macrocyclic ring systems are known for most of the ligand types that form discrete macrocyles. Additionally, there are a few examples for two-dimensional and three-dimensional coordination polymers containing sulfate, phosphate, vanadate, chromate, molybdate, and tungstate, indicating that these are also possible candidates for the formation of discrete macrocycles. 

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