Reversible capping/uncapping of phosphorous-centered Keggin-type polyoxoniobate clusters

Reversible capping/uncapping of phosphorous-centered Keggin-type polyoxoniobate clusters.

Caps in α-Keggin-type polyoxometalates [PM2Nb12O40](9-) (M: Nb[double bond, length as m-dash]O or V[double bond, length as m-dash]O) can be removed in basic condition to produce uncapped [PNb12O40](15-). Transmetalation or capping occurs from the reaction of [PNb14O42](9-) or [PNb12O40](15-) with either Sb2O3 or V2O5 to form [PSb2Nb12O40](9-) or [PV2Nb12O42](9-), respectively.

Catalytic consequences of composition in polyoxometalate clusters with Keggin structure.

Structural characterization of mono-ruthenium substituted Keggin-type silicotungstates.

We have synthesized the mono-ruthenium substituted Keggin-type silicotungstate [SiW(11)O(39)Ru(III)(H(2)O)](5-) (1a) by reaction of the mono-lacunary silicotungstate precursor [SiW(11)O(39)](8-) with Ru(acac)(3) under hydrothermal conditions and isolated as the caesium salt Cs(5)[SiW(11)O(39)Ru(III)(H(2)O)] (1). The DMSO-coordinated complex [SiW(11)O(39)Ru(III)(DMSO)](5-) (2a) was prepared by r...

Naphthyl-Containing Organophosphonate Derivatives of Keggin-Type Polyoxotungstates

New organophosphonate derivatives of monovacant Keggin-type polyoxotungstates that contain naphthyl groups have been synthesized and characterized in both solid state and solution. Single-crystal structural analysis shows that two phosphonate groups occupy the vacant position of the lacunary cluster unit in the isostructural compounds [N(C4H9)4]3[H(POC11H9)2(α-HBW11O39)] (TBA-1) and [N(C4H9)4]3...

Mechanistic consequences of composition in acid catalysis by polyoxometalate keggin clusters.

The kinetics and mechanism of ether and alkanol cleavage reactions on Brønsted acid catalysts based on polyoxometalate (POM) clusters are described in terms of the identity and dynamics of elementary steps and the stability of the transition states involved. Measured rates and theoretical calculations show that the energies of cationic transition states and intermediates depend on the propertie...