Controlling the Ring Curvature, Solution Assembly, and Reactivity of Gigantic Molybdenum Blue Wheels

We describe the synthesis, structure,
self-assembly, solution chemistry,
and mass spectrometry of two new gigantic decameric molybdenum blue
wheels, {Mo200Ce12} (1) and {Mo100Ce6} (2), by building block rearrangement
of the tetradecameric {Mo154} framework archetype and control
of the architecture’s curvature in solution from the addition
of Ce­(III). The assembly of 1 and 2 could
be directed accordingly by adjusting the ionic strength and acidity
of the reaction mixture. Alternatively, the dimeric cluster {Mo200Ce12} could be transformed directly to the monomeric
species {Mo100Ce6} upon addition of a potassium
salt. ESI-ion mobility mass spectra were successfully obtained for
both {Mo200Ce12} and {Mo100Ce6}, which is the first report in molybdenum blue chemistry
thereby confirming that the gigantic clusters are stable in solution
and that ion mobility measurements can be used to characterize nanoscale
inorganic molecules.