Direct Observation of the Formation Pathway of [Mo132] Keplerates ; DOI: 10.1021/acs.inorgchem.5b02570 URL: http://pubs.acs.org/doi/abs/10.1021/acs.inorgchem.5b02570 Filiació URV: SI ; The formation pathway of a closed spherical cluster [Mo132], starting from a library of building blocks of molybdate anions, has been reported. Electrospray ionization mass spectrometry, Raman spectroscopy, and theoretical studies describe the formation of such a complex cluster from a reduced and acidified aqueous solution of molybdate. Understanding the emergence of such an enormous spherical model cluster may lead to the design of new clusters in the future. Formation of such a highly symmetric cluster is principally controlled by charge balance and the emergence of more symmetric structures at the expense of less symmetric ones.