A water-soluble derivative of the polyoxovanadate {V₁₅E₆O₄₂} (E = semimetal) archetype enables the study of cluster shell rearrangements driven by supramolecular interactions. A reaction unique to E = Sb, induced exclusively by ligand metathesis in peripheral [Ni^II(ethylenediamine)] counterions, results in the nearly quantitative formation of the metastable alpha₁^* conformational isomer of the {V₁₄E₈O₄₂} cluster type. Contrary to all other polyoxovanadate shell architectures, this isomer comprises an inward-oriented vanadyl group and is ca. 50 and 12 kJ mol^–1 higher in energy than the previously isolated alpha and beta isomers, respectively. We discuss this unexpected reaction in light of supramolecular Sb-O···V and Sb- O···Sb contacts manifested in {V₁₄E₈O₄₂}₂ dimers observed in the solid state. ESI MS experiments confirm the stability of these dimers also in solution and in the gas phase. DFT calculations indicate that other, as of yet elusive isomers might be accessible as well.