High spin to low spin change induced by reductive chemistry with iron-substituted Dawson polyoxometalate

Chemical reduction of an iron(III) substituted Dawson 5-molybdo-12-tungsto-2-phosphate α2-K7[Fe(H2O)P2Mo5W12O61]⋅ 17H2O complex, with dithionite in aqueous solution is reported alongside with similar data for the monolacunary Dawson molybdo-tungsto-diphosphates α2-[P2Mo5W12O61]10 −. UV–vis absorption and low-temperature EPR (electron paramagnetic resonance) spectra indicate several distinct species and an unprecedented change of spin state at the ferric center, induced indirectly by reduction of the polyoxometalate framework.