Isolation of Blackberry-Shaped Nanoparticles of a Giant {Mo 72 Fe 30 } 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 {Mo72 Fe30 } cluster is instantaneously formed as the amorphous substance Na2 [Mo72 Fe30 O252 (CH3 COO)4 (OH)16 (H2 O)108 ]·180 H2 O (1). Compound 1 consists of aggregated nanovesicles of {Mo72 Fe30 } 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.