Polyoxotungstates now also with pentagonal units: supramolecular chemistry and tuning of magnetic exchange in {(M)M-5}(12)V-30 Keplerates (M = Mo, W)

The deliberate synthesis of the Keplerate [K-20 subset of {(W)W5O21(SO4)}(12)(VO)(30)(SO4)(H2O)(63)](18-) 1a with 20 pores all closed by K+ in a supramolecular fashion proves that it is possible to follow new routes in polyoxotungstate chemistry based on pentagonal {(W)W-5}-type units and to tune magnetic exchange couplings in {(M)M-5}(12)M'(30) type Keplerates.