Insight into the reactivity of in situ formed {(NbO2)3SiW9}: synthesis, structure, and solution properties of a trimeric polytungstosilicate trapping a {MnNb9} core

Abstract

A new trimeric cluster [(SiW₉Nb₃O₃₈)₃MnO₃(H₂O)₃]¹³⁻ (1) with three Keggin-type trilacunary SiW₉ units connected by a {MnNb₉} core were structurally characterized. The polyanion 1 features three corner-shared {Nb₃O₃} fragments that are linked to each other on two sides via three Nb–O–Nb bridges and by a {Mn^II} linker. To the best of our knowledge, polyanion 1 represents the first example of a trimeric niobotungstate cluster reported to date, and is revealed for the first time uniting a family of polytungstosilicate clusters. The formation of polyanion 1 exemplifies the reactivity of {(NbO₂)₃SiW₉} with a manganese metal ion, defining a new in situ synthetic strategy for {(NbO₂)₃SiW₉}-based derivatives, featuring POM chemistry between Nb/W mixed-addendum POMs and various transition-metal or lanthanide species.