Octanuclear Oxothiomolybdate(V) Rings: Structure and Ionic‐Conducting Properties

Abstract

A family of alkali salts of octanuclear oxothiomolybdate rings has been synthesized by crystallization of the [Mo(8)S(8)O(8)(OH)(8)[HMO(5)(H(2)O)]](3-) (noted HMo(8)M(3-); M=Mo, W) and [Mo(8)S(8)O(8)(OH)(8)(C(2)O(4))](2-) (noted Mo(8)ox(2-)) anions in an aqueous solution of ACl (A=Li, Na, K, Rb). Single-crystal X-ray diffraction experiments have been performed showing that the alkali salts exhibit a similar three-dimensional structure. Disordered alkali ions form columns to which the anionic rings are anchored. Ionic-conductivity measurements on pressed pellets have revealed two different behaviors. The lithium salts of HMo(8)M(3-) (M=Mo, W) are moderately good proton conductors at room temperature (sigma=10(-5) S cm(-1)) and the profile of conductivity as a function of relative humidity shows that the conductivity is due to surface-proton motion (particle-hydrate-type mechanism). On the other hand, the lithium salt of Mo(8)ox(2-) competes with the best crystalline lithium conductors at room temperature (sigma=10(-3) S cm(-1)), and (7)Li NMR experiments confirm the mobility of the lithium ions along the one-dimensional channels of this material.

Synthesis and Characterization of Octa- and Hexanuclear Polyoxomolybdate Wheels: Role of the Inorganic Template and of the Counterion

“…Such a family is of great interest for ionic conductivity measurements. Indeed, by analogy with previous results from our group on Li + and Na + salts of oxothiomolybdate rings, these salts could exhibit good ionic (protonic or alkali) conducting properties. Furthermore, the functionalization of Mo V can be envisioned by the use of R−SO 3 - , R−PO 3 2- , or R−AsO 3 2- (R = organic group) as an exogeneous ligand.…”

{Mo2O2X2}2+ (X = O, S), a magic building block for the design of wheel shaped metalates

“…Alkali cations are located in columns to which the anionic wheels are anchored [24]. Ionic conductivity measurements on pressed pellets revealed two different behaviors.…”

{Mo2O2X2}2+ (X = O, S), a Magic Building Block for the Design of Wheel Shaped Metalates

“…In contrast, the lithium salt of {Mo 8 ox} 2competes with the best solid lithium conductors at room temperature, r = 10 -3 S cm -1 . The mobility of lithium cations along 1D channels was confirmed by 7 Li NMR experiments [24].…”