Synthesis and Characterization of the Platinum-Substituted Keggin Anion α-H₂SiPtW₁₁O₄₀^4–

Abstract

Acidification of an aqueous solution of K8SiW11O39 and K2Pt(OH)6 to pH 4 followed by addition of excess tetramethylammonium (TMA) chloride yielded a solid mixture of TMA salts of H2SiPtW11O40(4-) (1) and SiW12O40(4-) (2). The former was separated from the latter by extraction into an aqueous solution and converted into tetra-n-butylammonium (TBA) and potassium salts TBA-1 and K-1. The α-H2SiPtW11O40(4-) was identified as a monosubstituted Keggin anion using elemental analysis, IR spectroscopy, X-ray crystallography, electrospray ionization mass spectrometry, (195)Pt NMR spectroscopy, (183)W NMR spectroscopy, and (183)W-(183)W 2D INADEQUATE NMR spectroscopy. Both TBA-1 and K-1 readily cocrystallized with their unsubstituted Keggin anion salts, TBA-2 and K-2, respectively, providing an explanation for the historical difficulty of isolating certain platinum-substituted heteropolyanions in pure form.

Atomically Dispersed Pt1–Polyoxometalate Catalysts: How Does Metal–Support Interaction Affect Stability and Hydrogenation Activity?

“…E Pt+[KA]-G refers to the total energy of the Pt adsorbed [polyoxometalate] on carbon system, E [polyoxometalate]-G is the energy of supported [polyoxometalate] cluster and E Pt means the energy for a Pt atom. In this article, negative values correspond to exothermic adsorption.As shown inTable 1, among different possible adsorption sites, one Pt atom clearly prefers to be coordinated with four oxygen atoms (4-H site) which matches well with the knowledge chemistry that Pt prefers to coordinate with four ligands [57][58]. When Pt is initially placed at the 3-H site, the atom will move upon energy optimization to an O br -O br or O c -O br bridge site.…”

Investigating the Transformations of Polyoxoanions Using Mass Spectrometry and Molecular Dynamics

“…K 8 [β 2 -SiW 11 O 39 ]·12H 2 O was synthesized according to the previously reported literature procedure. 54 K 8 [γ-SiW 10 O 36 ]·12H 2 O was synthesized according to the previously reported literature procedure, 46 though on a one-quarter scale (see Supporting Information for full details).…”

“… 42 This is in addition to the use of {γ-SiW 10 } for the direct epoxidation of olefins 43 or as a platform for the synthesis of single-molecule magnets, 44 while recent work has also demonstrated the formation of self-assembled monolayers of silicotungstate derivatives on Ag(111) 45 and the synthesis of catalytically active Pt-incorporating derivatives. 46 Understanding the fundamental behavior of these metal-oxide building blocks, particularly in the solution state (where POMs are increasingly exploited as homogeneous catalysts for instance), will therefore only increase in importance as applications for these materials continue to grow.…”

Polyoxometalates in solution: speciation under spotlight

“…38 Other nuclei. 11 B (NA = 80.42%; I = 3/2), 39 19 F (NA = 100%; I = 1/2), 40 27 Al (NA = 100%; I = 5/2) 41 and 195 Pt (NA = 33.7%; I = 1/2) 42 NMR spectroscopy are not as often used, but equally important for POM solution investigation.…”