Jahn-Teller Effects in a Vanadate-Stabilized Manganese-Oxo Cubane Water Oxidation Catalyst



We report Jahn–Teller effects in different oxidation states of the water oxidation catalyst [(Mn4O4)(V4O13)(OAc)3]n- and its activated form [(Mn4O4)(V4O13)(OAc)2(H2O)(OH)]n-. Based on all combinatorially possible Jahn–Teller axis arrangements of the Mn(III) atoms, the energetically stable minima are identified. We also derive five heuristic rules that associate a particular energetic cost with certain structural features, like crossings of multiple Jahn–Teller axes, the location of Jahn–Teller axes, or the ligand that is involved in a Jahn–Teller axis. It is found that the different oxidation states seem to localize on different Mn centers, giving rise to clear Jahn–Teller distortions, unlike in previous crystallographic findings where an apparent valence delocalization was found. We conclude that the combination of cubane-vanadate bonds that are chemically inert, cubane-acetate/water bonds that can be activated through a Jahn–Teller axis, and low activation barriers for intramolecular rearrangement of the Jahn–Teller axes plays an important role in the reactivity of this and related compounds.


Supplementary material

Supporting Information
Depictions and lists of all possible JT arrangements and their symmetry relations. Depictions of optimized minima. Bond lengths from pre-optimizations and full optimizations. Predicted relative energies of all possible JT arrangements based on the five presented rules. Overview over JT conversion pathways.
XYZ coordinates for precatalyst
Coordinates for all 12 stable minima of the precatalyst in XYZ format
XYZ coordinates for catalyst
Coordinates for all 20 stable minima of the catalyst in XYZ format