Synthesis, Structure, and Electrochemical Properties of [Na(SO3)2(RPO3)4MoV4MoVI14O49]5− (R = Propyl or t-Butyl)

Abstract

New mixed-valence polyoxometalate (POM)-organic hybrids, i.e., [Na(SO3)2(PrPO3)4MoV4MoVI14O49]5− and [Na(SO3)2(t-BuPO3)4MoV4MoVI14O49]5−, were synthesised and studied using crystallography, solution-phase 31P NMR, and electrochemistry. These species comprise four organic phosphonates bonded to a metal oxide cage. Derivatization was achieved by considering the pKa of the organic phosphonates and sulfite anions that acted as templates for the self-assembly of molybdate with POM. All the clusters were prepared in a water-acetonitrile mixed solvent system by a one-pot procedure and showed multi-step redox cycles, revealing that [Na(SO3)2(RPO3)4MoV4MoVI14O49]5− comprised a unique set of covalently grafted POM-organic hybrids with high redox activity.

Structural Phase Transitions of a Molecular Metal Oxide

“…Organic‐substituted basket POMs with other functional groups (R) were explored using R−PO 3 2− during the formation of [Mo V/VI 18 O 54 (SO 3 ) 2 ] m − . Derivatives were reported with phenyl, propyl‐, and tert ‐butyl‐phosphonate [23, 24] …”

Structural Phase Transitions of a Molecular Metal Oxide

“…Derivatives were reported with phenyl, propyl-, and tertbutyl-phosphonate. [23,24] Basket POMs usually have "handle" and "basket" parts ( Figure 1), where the metal ion X is located at the symmetrical position of the molecule. The Mo-O cage is reduced by 3-4 electrons in most cases, giving a mixed valence state, with the additional electrons being delocalized over the basket part.…”