The effect of the heteroatom (X=P, As, Si and Ge) on the geometrical and electronic properties of α-Keggin polyoxometalates (M=Mo, W and Nb) – A DFT investigation

DFT Insights into the Effect of Metal Substitution on the Catalytic Activity of Molybdenum-Based Heteropoly Acid in the Oxidation of Methacrolein to Methacrylic Acid

“…where k B is Boltzmann's constant, T is absolute temperature, h is Planck's constant, and ΔG ≠ is the difference in Gibbs free energy between the initial state and transition state of the reaction. of a central atom X (commonly seen were B, Al, Ga, Si, Ge, P, As, S, and so on), 45,46 coordination atoms M (mainly including Mo, W, V, and Nb), 46,47 Molybdenum-based HPA compounds had been successfully applied in the selective oxidation of MAL to MAA due to their suitable acid and redox properties. 1,2 To study the influence of transition metals with similar properties in the fifth and sixth secondary groups on the redox properties of phosphorus molybdenum HPAs, the models were established by replacing one molybdenum atom with tungsten, vanadium, niobium, and tantalum atoms, namely, PMo 11 Figure 2 shows diagrams of substituted HPAs after structure optimization.…”

Study on the incorporation of various elements into the Keggin lacunary-type phosphomolybdate [PMo9O34]9− and subsequent purification of the polyoxometalates by nanofiltration

“…[18][19][20][21][22][23][24] Quantum chemical calculations have shown that the incorporation of the different metals alters the shape of the POMs, where the bond distances between the oxygen atoms and upcoming metal change with respect to their atomic radii. 25 These distortions in M-O bonds originate from a pseudo Jahn-Teller vibronic instability at high symmetry configurations. 26 There are two possible pathways to synthesize element-substituted Keggin-type POMs: the self-assembly process, 14,15,27,28 or, alternatively, via the formation of a lacunary structure.…”

“…18–24 Quantum chemical calculations have shown that the incorporation of the different metals alters the shape of the POMs, where the bond distances between the oxygen atoms and upcoming metal change with respect to their atomic radii. 25 These distortions in M–O bonds originate from a pseudo Jahn–Teller vibronic instability at high symmetry configurations. 26…”

Heteroatom-Modulated Assembly of Hexalanthanoid-Containing Polyoxometalate-Based Coordination Networks

“…In contrast, POMs with high-nuclearity Ln clusters remain relatively underexplored because of the hydrolysis of Ln ions and their larger size and higher coordination numbers. Moreover, most of these systems are 0D-culsters; only the Ln 26 -cluster POM of [Ln 27 Ge 10 W 106 O 406 (OH) 4 (H 2 O) 24 ] 5 − was extended to inorganic–organic hybrid frameworks through TM ions, and the Ce 10 -cluster [Ce 10 P 6 W 48 O 183 (CO 3 )­(OH) 6 (H 2 O) 11 ] − presented a 2D graphite-like framework through peripheral Ce 3+ ions. Thus, the rational synthesis of POMs integrating high-nuclearity Ln clusters and those further assembled into extended networks remains a challenge, studies of which are ongoing.…”

“…In fact, organophosphonates as multidentate ligands and appropriate electro-donating groups are promising candidates for the fabrication of POMs featuring high-nuclearity Ln clusters . Furthermore, both experimental and theoretical studies show the importance of the heteroatoms in affecting the coordination geometries and the electronic structure of the POMs, whereas no study has encompassed the investigation of tuning the dimensionality of POM-based materials via changing the heteroatoms.…”