Synthesis and characterization of the `Japanese rice-ball'-shaped Molybdenum Blue Na 4 [Mo 2 O 2 (OH) 4 (C 6 H 4 NO 2 ) 2 ] 2 [Mo 120 Ce 6 O 366 H 12 (OH) 2 (H 2 O) 76 ]∼200H 2 O.

The hybridized lanthanide-containing molybdenum blue (Ln-MB) wheel Na 4 [Mo 2 O 2 (OH) 4 (C 6 H 4 NO 2 ) 2 ] 2 [Mo 120 Ce 6 O 366 H 12 (OH) 2 (H 2 O) 76 ]∼200H 2 O ({Mo 2 (C 6 H 4 NO 2 ) 2 } 2 {Mo 120 Ce 6 }) was assembled in an aqueous one-pot synthesis. The Ln-MB was hybridized with 2-picolinic acid through the generation of the organometallic counter-ion [Mo 2 O 2 (OH) 4 (C 6 H 4 NO 2 ) 2 ] 2+ . Control experiments demonstrated that the position of the carboxylic acid group (2-position to the N atom) in the hybridization component is critical in yielding single crystals of Ln-MB. In addition to single-crystal X-ray diffraction (XRD) analysis, which revealed a `Japanese rice-ball'-shaped Ln-MB as the anion, elemental analyses, IR spectroscopy, and thermogravimetric analysis (TGA) were performed to confirm its structure and composition. Bond-valence-sum calculations (BVS) revealed that {Mo 2 (C 6 H 4 NO 2 ) 2 } 2 {Mo 120 Ce 6 } is composed of a 24-electron reduced anionic ring, which was confirmed by Vis-NIR spectroscopy.