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.