Electronic Control of Spin Coupling in Keplerate-Type Polyoxomolybdates

We recently identified a synthetic procedure for the isolation of Keplerate structures based on the reaction of multivalent heterometal centers with larger polyoxomolybate(V/VI) units that coexist in a reaction solution at a certain pH. This approach yielded Keplerate clusters of the type {Mo72Mo8V22},[16] {Mo72V15Fe7Mo8}, and {Mo72V11Fe11Mo8},[14] which were obtained as kinetic products within minutes to a few hours following addition of KCl. Herein, we demonstrate for an analogous reaction system, how novel {Mo72Fe30} Keplerate species with partially reduced {(Mo)Mo5} building blocks (Robin–Day class III) can be identified, based on Raman spectroscopy time profiles of acidified aqueous molybdate reaction solutions