NOBLE METAL POMs

Polyoxometalates (POMs, discrete nanosized metal oxo anions) are an increasingly fascinating object of study owing to their enormous structural diversity and unique combination of properties, such as thermal and oxidative stability, tunability of acidity and redox activity, and ability to activate easily accessible “green” oxidants (O₂ and H₂O₂), thus making them attractive for applications in many different areas, for example, in catalysis, magnetism, nanotechnology, and medicine. Although this class of compounds was discovered as far back as 1826, until recently POMs were known predominantly for Group 5 and 6 addenda metals in high oxidation states (e.g. W⁶⁺, V⁵⁺).

In 2008 we reported the synthesis, structure, and preliminary catalytic studies of [Pd_^II13As₈^VO₃₄(OH)₆]^8– (Pd₁₃As₈), the first member of a novel subclass of polyoxoanions built exclusively of d⁸ Pd^II addenda metal ions. All Pd^II ions in Pd₁₃As₈ retain square-planar coordination geometry, in sharp contrast to all other known discrete POMs, which generally contain metal centers in octahedral environments. Even more recently we have shown the possibility of preparing other hetero-13-palladate derivatives, in which the {AsO₄}^3- capping fragments in Pd₁₃As₈ are replaced by lone-pair-containing {Se^IVO₃}^2- and organic-functionalized {PhAs^VO3}^2- groups. We also demonstrated the existence of another structural type of polyoxopalladate, [Pd₁₅P₁₀O₅₀]^20- (Pd₁₅P₁₀), which comprises 15 Pd^II addenda ions and adopts the shape of a star pentagon. We also discovered that the Pd₁₂L₈ heteropolypalladate shell in the above species can stabilize unusual coordination numbers and geometries for the encapsulated Pd^II ion, including unprecedented eight-fold cubic coordination. Wickleder et al. reported the solid-state d⁷ metal cluster anion [Pt^III₁₂O₈(SO₄)₁₂]^4-, which is composed of six dumbbell-shaped [Pt₂]⁶⁺ ions linked by oxo and sulfate bridges.

There is great interest in soluble late-transition-metal oxo complexes as potential models of so-called MOx “suboxide clusters”, which have been proposed to be crucial intermediates in noble-metal-based heterogeneous catalytic oxidation systems. Furthermore, noble-metal-based materials are important as catalysts in numerous industrially relevant processes and devices, including low-temperature and environmentally benign O₂-based oxidations, reforming, automobile converters, and fuel cells. This background warrants an extension of our polypalladate(II) work to other d⁸ metal ions (e.g. platinum(II), gold(III)).

Noble Metal in Action

Ulrich Kortz, Chemistry professor at Jacobs University, and his team report the synthesis of a novel, discrete noble metal-oxide, containing a record number of 22 palladium atoms, as well as two central copper ions. In addition to its high catalytic potential, this {Cu2Pd22} cluster compound also exhibits very unusual intramolecular magnetic interactions. The study has now been published as a “Very Important Paper” in the Angewandte Chemie International Edition.

Noble Metal Polyoxometalate Research
featured in Platinum Metals Review

Platinum Metals Rev., 2014, 58, (1), 40

Selected Publications

• Last piece of the puzzle: lead-assisted assembly of an arsenopalladate nanostar as antitumor metallodrug 
  Zhao, Y.; Li, C.-L.; Chen, C.-Q.; Du, J.; Kortz, U.; Gong, T.; Yang, P. Inorg. Chem. Front. 2024 [Read Online]
• Gallium(III)- and Thallium(III)-Encapsulated Polyoxopalladates: Synthesis, Structure, Multinuclear NMR and Biological Activity Studies
  Ma, T.; Ma. X.; Lin, Z.; Zhang, J.; Yang, P.; Csupász, T.; Tóth, I.; Misirlic-Dencic, S.; Isakovic, M. A.; Lembo, D.; Donalisio, M.; Kortz, U. Inorg. Chem. 2023, 62, 33, 13195-13204. [Read Online]
• Pt^IV-Containing Hexaplatinate(II) [Pt^IVPt^II₆O₆(AsO₂(CH₃)₂)₆]^2- and Hexapalladate(II) [Pt^IVPd^II₆O₆(AsO₂(CH₃)₂)₆]^2-
  Zhang, J.; Bhattacharya, S.; Khsara, B. E.; Nisar, T.; Müller, A. B.; Besora, M.; Poblet, J. M.; Wagner, V.; Kuhnert, N.; Kortz, U. Inorg. Chem. 2023, 62, 33, 13184-13194 [Read Online]
• Mixed-Valent Palladium(IV/II)-Oxoanion, [Pd^IVO₆Pd^II₆((CH₃)₂AsO₂)₆]^2-
  Ma, X.; Bhattacharya, S.; Nisar, T.; Müller, A. B.; Wagner, V.; Kuhnert, N.; Kortz, U. Chem. Commun. 2023, 59, 904-907. [Read Online]
• Host–Guest Chemistry in Discrete Polyoxo-12-Palladate(II) Cubes [MO₈Pd₁₂L₈]^n– (M = Sc^III, Co^II, Cu^II, L = AsO₄^3–; M = Cd^II, Hg^II; L = PhAsO₃^2–): Structure, Magnetism, and Catalytic Hydrogenation
  Yang, P.; Elcheikh Mahmoud, M.; Xiang, Y.; Lin, Z.; Ma, X.; Christian, J. H.; Bindra, J. K.; Kinyon, J. S.; Zhao, Y.; Chen, C.; Nisar, T.; Wagner, V.; Dalal, N. S.; Kortz, U. Inorg. Chem. 2022, 61, 18524–18535. [Read Online]
• Discrete, Cationic Palladium(II)-Oxo Clusters via f-Metal Ion Incorporation and their Macrocyclic Host-Guest Interactions with Sulfonatocalixarenes
  Bhattacharya, S.; Barba-Bon, A.; Zewdie, T. A.; Müller, A. B.; Nisar, T.; Chmielnicka, A.; Rutkowska, I. A.; Schürmann, C. J.; Wagner, V.; Kuhnert, N.; Kulesza, P. J.; Nau, W. M.; Kortz, U. Angew. Chem. Int. Ed. 2022, 61, e202203114. [Read Online]
• Towards size-controlled deposition of Pd nanoparticles from polyoxometalate precursors: an Electrochemical Scanning Tunneling Microscopy study
  Bock, N.; Clercq, A. D.; Seidl, L.; Kratky, T.; Ma, T.; Günther, S.; Kortz, U.; Heiz, U.; Esch, F. ChemElectroChem. 2021, 8, 1280-1288. [Read Online]
• Discovery and Supramolecular Interactions of Neutral Palladium-Oxo Clusters Pd₁₆ and Pd₂₄
  Bhattacharya, S.; Basu, U.; Haouas, M.; Su, P.; Espenship, M. F.; Wang, F.; Solé-Daura, A.; Taffa, D. H.; Wark, M.; Poblet, J. M.; Laskin, J.; Cadot, E.; Kortz, U. Angew. Chem. Int. Ed. 2021, 60, 3632–3639. [Read Online, Open Access]
• Shape and Size Tuning of Bi^III-Centered Polyoxopalladates: High Resolution ²⁰⁹Bi NMR and ^205/206Bi Radiolabelling for Potential Pharmaceutical Applications
  Manna, P.; Szücs, D.; Csupász, T.; Fekete, A.; Szikra, D.; Lin, Z.; Gáspár, A.; Bhattacharya, S.; Zulaica, A.; Tóth, I.; Kortz, U. Inorg. Chem. 2020, 59, 16769–16782. [Read Online] (Featured Article)
• Palladium(II)-containing Tungstoarsenate(V), [Pd^II₄(As₂W₁₅O₅₆)₂]^16-, and its Catalytic Properties
  Rajan, A.; Mougharbel, A. S.; Bhattacharya, S.; Nisar, T.; Wagner, V.; Kortz, U. Inorg. Chem. 2020, 59, 13042–13049. [Read Online]
• Polyoxopalladate-loaded Metal-Organic Framework (POP@MOF): Synthesis and Heterogeneous Catalysis
  Bhattacharya, S.; Ayass, W. W.; Taffa, D. H.; Nisar, T.; Balster, T.; Hartwig, A.; Wagner, V.; Wark, M.; Kortz, U. Inorg. Chem. 2020, 59, 10512−10521. [Read Online].
• Indium in Polyoxopalladate(II) Chemistry: Synthesis of All-acetate-capped [InPd₁₂O₈(OAc)₁₆]^5- and Controlled Transformation to Phosphate-capped Double-cube and Mono-cube
  Ma, T.; Yang, P.; Parris, J.; Csupasz, T.; Li, M.-X.; Bányai, I.; Tóth, I.; Lin, Z.; Kortz, U. Inorg. Chem. 2019, 58, 15864-15871. [Read Online]
• Tetravalent Metal Ion Guests in Polyoxopalladate Chemistry: Synthesis and Anticancer Activity of [MO₈Pd₁₂(PO₄)₈]^12– (M = Sn^IV, Pb^IV)
  Yang, P.; Ma, T.; Lang, Z.-L.; Misirlic-Dencic, S.; Isaković, A. M.; Bényei, A.; Čolović, M. B.; Markovic, I.; Krstić, D. Z.; Poblet, J. M.; Lin, Z.; Kortz, U. Inorg. Chem. 2019, 58, 11294-11299. [Read Online]
• A ²²⁴Ra-labeled Polyoxopalladate as Putative Radiopharmaceutical
  Gott, M.; Yang, P.; Kortz, U.; Stephan, H.; Pietzsch, H.-J.; Mamat, C. Chem. Commun. 2019, 55, 7631-7634.  [Read Online]
• Discovery of Polyoxo-Noble-Metalate-Based Metal-Organic Frameworks
  Bhattacharya, S.; Ayass, W. W.; Taffa, D. H.; Schneemann, A.; Semrau, A. L.; Wannapaiboon, S.; Altmann, P. J.; Pöthig, A.; Nisar, T.; Balster, T.; Burtch, N. C.; Wagner, V.; Fischer, R. A.; Wark, M.; Kortz, U. J. Am. Chem. Soc. 2019, 141, 3385−3389. [Read Online]
• Palladium(II) Incorporation in the All-Inorganic Cryptand [As₄W₄₀O₁₄₀]²⁸⁻: Synthesis and Structural Characterization of [Pd₂Na₂KAs₄W₄₀O₁₄₀(H₂O)]²¹⁻
  Lin, Z.; Izarova, N. V.; Mehari, F. T.; Kortz, U. Z. Anorg. Allg. Chem.  2018, 644, 1379–1382. [Read Online]
• Discovery and Evolution of Polyoxopalladates
  Yang, P.; Kortz, U. Acc. Chem. Res. 2018, 51, 1599−1608.[Read Online]
• Tuning of Polyoxopalladate Macroanionic Hydration Shell via Countercation Interaction
  He, J.; Li, H.; Yang, P.; Haso, F.; Wu, J.; Li, T.; Kortz, U.; Liu, T. Chem. Eur. J. 2018, 24, 3052–3057. [Read Online]
• Rational Design of Organically Functionalized Polyoxopalladates and Their Supramolecular Properties
  Yang, P.; Li, H.; Ma, T.; Haso, F.; Liu, T.; Fan, L.; Lin, Z.; Hu, C.; Kortz, U. Chem. Eur. J. 2018 , 24, 2466–2473. [Read Online]
• Size and Charge Effect of Guest Cations in Formation of Polyoxopalladates: A Theoretical and Experimental Study
  Lang, Z.; Yang, P.; Lin, Z.; Yan, L.; Li, M.-X.; Carbó, J. J.; Kortz, U.; Poblet, J. M. Chem. Sci. 2017, 8, 7862–7872. [Read Online]
• Discrete Silver(I)-Palladium(II)-Oxo Nanoclusters, {Ag₄Pd₁₃} and {Ag₅Pd₁₅}, and the Role of Metal–Metal Bonding Induced by Cation Confinement
  Yang, P.; Xiang, Y.; Lin, Z.; Lang, Z; Jiménez-Lozano, P.; Carbó, J. J.; Poblet, J. M.; Fan, L.; Hu, C.; Kortz, U. Angew. Chem. Int. Ed.  2016, 55, 15766 –15770. [Read Online]
• The Polyoxo-22-palladate(II), [Na₂Pd^II₂₂O₁₂(As^VO₄)₁₅(As^VO₃OH)]^25–
  Izarova, N. V.; Lin, Z.; Yang, P.; Kondinski, A.; Vankova, N.; Heine, T.; Kortz, U. Dalton Trans. 2016, 45, 2394–2398. [Read Online]
• Molecular spin qubits based on lanthanide ions encapsulated in cubic polyoxopalladates: design criteria to enhance quantum coherence
  Baldoví, J. J.; Rosaleny, L. E.; Ramachandran, V.; Christian, J.; Dalal, N. S.; Clemente-Juan, J. M.; Yang, P.; Kortz, U.; Gaita-Ariño, A.; Coronado, E. Inorg. Chem. Front. 2015, 2, 893-897. [Read Online]
• Exploring the Effect of Surface Functionality on the Self-Assembly of Polyoxopalladate Macroions
  Haso, F.; Yang, P.; Gao, Y.; Yin, P.; Li, H.; Li, T.; Kortz, U.; Liu, T.  Chem. Eur. J. 2015, 21, 9048-9052. [Read Online]
• Alkaline Earth Guests in Polyoxopalladate Chemistry: From Nanocube to Nanostar via an Open-Shell Structure
  Yang, P.; Xiang, Y.; Lin, Z.; Bassil, B. S.; Cao, J.; Fan, L.; Fan, Y.; Li, M.; Jiménez-Lozano, P.; Carbó, J. J.; Poblet, J. M.; Kortz, U. Angew. Chem. Int. Ed.  2014, 53, 11974-11978. [Read Online]
• The mixed gold-palladium polyoxo-noble-metalate, [NaAu^III₄Pd^II₈O₈(AsO₄)₈]^11-
  Izarova, N. V.; Kondinski, A.; Vankova, N.; Heine, T.; Jäger, P.; Schinle, F.; Hampe, O.; Kortz, U.  Chem. Eur. J.  2014, 20, 8556-8560. [Read Online]
• Polyoxopalladates Encapsulating 8-Coordinated Metal Ions, [MO₈Pd^II₁₂L₈]^n-
  (M = Sc^III, Mn^II, Fe^III, Co^II, Ni^II, Cu^II, Zn^II, Lu^III; L = PhAsO₃^2-, PhPO₃^2-, SeO₃^2-)
  Barsukova-Stuckart, M.; Izarova, N. V.; Barret, R. A.; Wang, Z.; van Tol, J.; Kroto, H. W.; Dalal, N. S.; Jiménez-Lozano, P.; Carbó, J. J.; Poblet, J. M.; von Gernler, M. S.; Drewello, T.; de Oliveira, P.; Keita, B.; Kortz, U. Inorg. Chem. 2012, 51, 13214-13228. [Read Online]
• The Selenite-capped Polyoxo-4-aurate(III), [Au^III₄O₄(Se^IVO₃)₄]^4-
  Xiang, Y.; Izarova, N. V.; Schinle, F.; Hampe, O.; Keita, B.; Kortz, U. Chem. Commun. 2012, 48, 9849-9851. [Read Online]
• Noble Metals in Polyoxometalates
  Izarova, N. V.; Pope, M. T.; Kortz, U. Angew. Chem. Int. Ed. 2012, 51, 9492-9510. [Read Online]
• 3d Metal Ions in Highly Unusual Eight-Coordination: The Phosphate-Capped Dodecapalladate(II) Nanocube
  Barsukova-Stuckart, M.; Izarova, N. V.; Barrett, R.; Wang, Z.; van Tol, J.; Kroto, H. W.; Dalal, N. S.; Keita, B.; Heller, D.; Kortz, U. Chem. Eur. J. 2012, 18, 6167-6171. [Read Online]
• Synthesis and Characterization of the Di-Copper(II)-Containing 22-Palladate(II), [Cu^II₂Pd^II₂₂P^V₁₂O₆₀(OH)₈]^20-
  Barsukova-Stuckart, M.; Izarova, N. V.; Jameson, G. B.; Ramachandran, V.; Wang, Z.; van Tol, J.; Dalal, N. S.; Ngo Biboum, R.; Keita, B.; Nadjo, L.; Kortz, U. Angew. Chem. Int. Ed. 2011, 50, 2639-2642. [Read Online]
• A Noble Metalate Bowl: The Polyoxo-6-Vanado(V)-7-Palladate(II) [Pd₇V₆O₂₄(OH)₂]^6-
  Izarova, N. V.; Vankova, N.; Banerjee, A.; Jameson, G. B.; Heine, T.; Schinle, F.; Hampe, O.; Kortz, U. Angew. Chem. Int. Ed. 2010, 49, 7807-7811. [Read Online]
• Polyoxopalladates Encapsulating Yttrium and Lanthanide Ions, [X^IIIPd^II₁₂(AsPh)₈O₃₂]^5- (X = Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu)
  Barsukova, M.; Izarova, N. V.; Ngo Biboum, R.; Keita, B.; Nadjo, L.; Ramachandran, V.; Dalal, N. S.; Antonova, N. S.; Carbó, J. J.; Poblet, J. M.; Kortz, U. Chem. Eur. J. 2010, 16, 9076-9085. [Read Online]
• Polyoxometalates made of Gold: The Polyoxoaurate [Au^III₄As^V₄O₂₀]^8-
  Izarova, N. V.; Vankova, N.; Heine, T.; Ngo Biboum, R.; Keita, B.; Nadjo, L.; Kortz, U., Angew. Chem. Int. Ed. 2010, 49, 1886-1889. [Read Online]
• Self-assembly of star-shaped heteropoly-15-palladate(II)
  Izarova, N. V.; Ngo Biboum, R.; Keita, B.; Mifsud, M.; Arends, I. W. C. E.; Jameson, G. B.; Kortz, U. Dalton Trans. 2009, 9385-9387. [Read Online]
• Heteropoly-13-Palladates(II) [Pd^II₁₃(As^VPh)₈O₃₂]^6- and [Pd^II₁₃Se^IV₈O₃₂]^6-
  Izarova, N. V.; Dickman, M. H.; Ngo Biboum, R.; Keita, B.; Nadjo, L.; Ramachandran, V; Dalal, N. S.; Kortz, U. Inorg. Chem. 2009, 48, 7504-7506. [Read Online]
• Self Assembly of a Heteropolyoxopalladate Nanocube, [Pd^II₁₃As^V₈O₃₄(OH)₆]^8-
  Chubarova, E. V.; Dickman, M. H.; Keita, B.; Nadjo, L.; Mifsud, M.; Arends, I. W. C. E.; Kortz, U. Angew. Chem. Int. Ed. 2008, 47, 9542-9546. [Read Online]

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