Steering polyoxometalates transformation from octahedral to tetrahedral coordination by counter-cations

Polyoxometalates (POMs) are intriguing catalysts for various reactions. However, the function of their counter-cations is overlooked. Here, we show that flexible counter-cations of methyltrioctylammonium can trigger polyoxovanadates to transform from octahedrally coordinated H2V10O284- to tetrahedrally coordinated V10O262-. This structural transformation advances performance tunability in POMs chemistry and improves catalyst design.