Alkaline Earth Guests in Polyoxopalladate Chemistry: From Nanocube to Nanostar via an Open‐Shell Structure

Abstract

The three novel, discrete palladium(II)-oxo clusters [CaPd12O8(PhAsO3)8](6-) (CaPd12), [SrPd12O6(OH)3(PhAsO3)6(OAc)3](4-) (SrPd12), and [BaPd15O10(PhAsO3)10](8-) (BaPd15) encapsulating alkaline earth metal ions were prepared and fully characterized by a multitude of solution and solid-state physicochemical techniques. We have discovered a structure-directing template effect induced by the respective size of the alkaline earth guest ion, which determines the detailed condensation arrangement of the peripheral Pd(II)-oxo shell. The unprecedented SrPd12 with an open-shell type structure is of particular importance and reflects a successful strategy for deliberate design of new structural classes of polyoxo-noble-metalates. Furthermore, the unusual acetate-water ligand exchange phenomenon renders SrPd12 as a promising candidate for noble-metal-based catalysis.

Discrete Silver(I)‐Palladium(II)‐Oxo Nanoclusters, {Ag4Pd13} and {Ag5Pd15}, and the Role of Metal–Metal Bonding Induced by Cation Confinement

“…[9] Recent advances elucidated that the respective size of the guest M allows the detailed condensation arrangement of the peripheral Pd II -oxo shell to be tuned. [10] Nevertheless,asystematic study on the structure-directing effects induced by other noble metal ions besides Pd II has thus far been rather unexplored, although we have demonstrated that it is possible to merge Pd II and Au III into one polyanion. [11] Compared to single-component nanocatalysts,t he catalytic performance of composite nanostructured systems, which are composed of two or more noble metal elements, tends to improve dramatically with higher activity,prolonged lifetime,a nd optimized selectivity,a saunique ensemble of functions from each individual component, hence overcoming the limitation of their single-metal counterparts.…”

“…[8a,c] However,i ti sd ifficult to directly assign the signals to specific phosphorus atoms owing to the closely spaced resonances ( Figure S4). Therefore,ESI-MS was used to obtain more insight on the stability of both polyanions in both solution and gas phases.T he ESI-MS spectrum of Na-Ag 4 Pd 13 indicates that all major envelopes originate from the Pd 13 core structure ( Figure S5a) 15 shows ad istribution of peaks which can all be unambiguously assigned to ion pairs related to the intact AgPd 15 core (with one Ag I ion present in the center of the polyanion channel), appearing as an ensemble of adducts with different numbers of external Ag I guests ranging from 1t o5( Figure S5b) 10 AgPd 15 ]} 4À ,respectively.These ESI-MS spectra demonstrate that the AgPd 15 core structure is stable in aqueous solution as well as in the gas-phase.A dditional MS assignments are summarized in Table S3.…”

A Strategy for Breaking Polyoxometalate‐based MOFs To Obtain High Loading Amounts of Nanosized Polyoxometalate Clusters to Improve the Performance of Dye‐sensitized Solar Cells

“…The dopantc ould be an oble metal, [14] metal ions, [15][16][17][18][19] or non-metal ions. [28][29][30][31][32][33][34][35] Polyoxoanions have empty do rbitals in their structures to accept electrons withouts tructure changes. [24][25][26][27] POMs,a saclass of inorganic anionic clusters, have been extensively applied in magnetism, materials science, nonlinear optics, electrical, catalysis, optical, energy,a nd medicineo wing to their redox properties, charged istribution, versatile properties, and rich topology.…”

Ca2+‐Driven Self‐Assembly of POMs into 2D/3D Coordination Polymers

“…[9][10][11][12][13][14] The majority of the reports related to POM-based heterometallic compounds cover examples with Cu as a second metal, [15][16][17] while only a few publications mention the anions' combination with cobalt. [27] Inspired by the reported structure-directing template effect of the metals on the formation of POMs, we decided to study the influence of Ca 2+ and Sr 2+ ions on phosphomolybdate-based structures. [20,21] Another intriguing possibility is the use of alkaline-earth metals as promising templates for discovering new binding motifs with POMs.…”

“…[23] There are also a number of vanadiumbased polyanions linked by alkaline-earth metals. [27] Inspired by the reported structure-directing template effect of the metals on the formation of POMs, we decided to study the influence of Ca 2+ and Sr 2+ ions on phosphomolybdate-based structures. [27] Inspired by the reported structure-directing template effect of the metals on the formation of POMs, we decided to study the influence of Ca 2+ and Sr 2+ ions on phosphomolybdate-based structures.…”