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.