Abstract:
The synthesis, single crystal structure, spectral, thermal and electrical properties of a hexarubidium heptamolybdate [Rb sub(6)(H sub(2)O) sub(4)(Mo sub(7) O sub(24))] 1 is reported. The bridging binding modes of the unique (Mo sub(7) O sub(24))sup(6-) ion and the four crystallographically independent coordinated water molecules results in coordination numbers ranging from 8 to 10 for the six unique Rb(I) ions in 1. Thermal decomposition of 1 results in the formation of an anhydrous residue of composition 7MoO sub(3).3Rb sub(2)O. The cyclic voltammogram of an aqueous solution of 1 exhibits a single redox event characteristic of (Mo sub(7) O sub(24))sup(6-) anion. Solution conductivity studies reveal the presence of hydrated Rb + cations and uncoordinated (Mo sub(7) O sub(24))sup(6-) anions. A comparative study of several alkali-metal heptamolybdates reveals a rich structural chemistry in terms of the binding modes of the (Mo sub(7) O sub(24))sup(6-) anion.
