Isolation of Blackberry-Shaped Nanoparticles of a Giant {Mo72Fe30} Cluster and Their Transformation to a Crystalline Nanoferric Molybdate.

When an aqueous solution of sodium molybdate is added to an aqueous solution of ferric chloride, acidified with acetic acid, a giant {Mo72Fe30} cluster is instantaneously formed as the amorphous substance Na2[Mo72Fe30O252(CH3COO)4(OH)16(H2O)108]·180 H2O (1). Compound 1 consists of aggregated nanovesicles of {Mo72Fe30} clusters, as confirmed by field-emission scanning electron microscopy and transmission electron microscopy images of 1. An aqueous suspension of 1 upon moderate heating results in the formation of crystalline nanoferric molybdate, which gives insight into understanding the formation of a yellow coating mineral, ferrimolybdite, frequently found on the ores of molybdenum.