Coordination-Driven Self-Assembly of a 2D Graphite-Like Framework Constructed from High-Nuclear Ce₁₀ Cluster Encapsulated Polyoxotungstates

Abstract

It is challenging to explore and prepare high-nuclear lanthanide (Ln) cluster-encapsulated polyoxometalates (POMs). Herein, we fabricate an unprecedented Ce10-cluster-embedded polyoxotungstate (POT) (TMA)14H2[Ce(III)(H2O)6]{[Ce(IV)7Ce(III)3O6(OH)6(CO3)(H2O)11][(P2W16O59)]3}·41H2O (1) (TMA = tetramethyleneamine) by coordination-driven self-assembly strategy, which contains the largest Ce cluster [Ce(IV)7Ce(III)3O6(OH)6(CO3)(H2O)11] (Ce10) in all the Ln-containing POM chemistry to date. Self-assembly of the in situ dilacunary [P2W16O59](12-) fragments and mixed Ce(3+) and Ce(4+) ions by means of coordination-driven force results in a novel 2D graphite-like framework constructed from mixed-valent cerium(III/IV) cluster {Ce10} encapsulated poly(POT) units and Ce(3+) ions. The most remarkable feature is that the skeleton of the centrosymmetric Ce10-cluster-embedded POT trimer contains three dilacunary [P2W16O59](12-) fragments trapping a novel {Ce10} cluster via 18 terminal-oxo and three μ4-oxo atoms.

A Nonclassical Polyoxoanion [P3W6(O2)6(OH)2O22]7– Constructed by Two {PW3(O2)3(OH)O9} Subunits and a {PO4} Group

“…However, the intensity gradually decays along with the longer time, which may be due to the slow cloudiness in solution at room temperature. Unexpectedly, the peak at δ = 1.18 ppm gradually disappears after 12 hours, which may be attributed to the partial decomposition of the anion skeleton (Figure b) …”

Redox Active Hexanuclear Mixed Valence Dicationic Ce(III)/Ce(IV) Coordination Clusters

“…Cerium is a unique f‐block element with two possible redox active oxidation states (III/IV), [ 1 ] structural diversities and various applications in different fields of chemistry. [ 1–15 ] Some of the cerium complexes are extremely interesting for studying multiple bonds between Ce‐atom and C c arbene ‐ [polarized covalent Ce(IV)–C σ‐ and π‐multiple bond interactions with significant covalent component], [ 2 ] nitrogen‐ [ 3 ] and oxygen‐atoms. [ 2,3 ] Complexes containing such chemical bonds are highly reactive towards certain reactants.…”

“…The isolation and characterization of mixed valence Ce complexes have been rarely documented so far. [ 9,10 ] In this context, it is noteworthy to mention that only one mixed valence Ce IV Ce III 2 complex, [ 9 ] an anti‐ferromagnetically coupled mixed valence Ce IV 7 Ce III 3 [ 10a ] unit encapsulated within polyoxotungstanates and two other high nuclearity Ce‐clusters [ 10b ] have been reported till date (Scheme 1).…”

“…Syntheses and characterization of polynuclear coordination clusters of mixed valence Ce(III/IV) ions are rare. [ 9–10 ] Schiff base ligand (containing two phenolic OH groups) stabilized the mono nuclear Ce(III)/Ce(IV) complexes [ 16,28 ] and the dinuclear Ce(IV) complexes. [ 16 ] Here, we report the syntheses, isolation and characterization of dicationic complexes of general formula M 2+ (X – ) 2 [for 1 2+ and 2 2+ : M = Ce IV 2 Ce III 4 (µ 4 ‐O) 2 (L–R) 4 (val) 6 (H 2 O) 2 , R = H for 1 2+ , R = Me for 2 2+ , X = Ce III 2 (val) 3 (NO 3 ) 4 , for 3 2+ : R = H, X = NO 3 ], containing two µ 4 ‐O 2– bridges [H 2 L–R = diprotic Schiff base ligand, R = H, Me].…”

Four‐Shell Polyoxometalates Featuring High‐Nuclearity Ln26 Clusters: Structural Transformations of Nanoclusters into Frameworks Triggered by Transition‐Metal Ions

“…The majority of reported Ln‐substituted POMs encapsulate separated Ln 3+ ions or small Ln clusters with nuclearities ranging from two to six . To the best of our knowledge, the nuclearity of the largest Ln cluster that has been incorporated into a POM is only ten, and such a large Ln cluster was only observed in {[Ce 10 O 6 (OH) 6 (CO 3 )(H 2 O) 11 ][(P 2 W 16 O 59 )] 3 } . Notably, a few fascinating POMs with more than 15 Ln centers have been made, including 16‐Ce‐containing {As 12 Ce 16 (H 2 O) 36 W 148 O 524 }, 20‐Ce‐containing {Ce 20 Ge 10 W 100 O 376 (OH) 4 (H 2 O) 30 }, 24‐Cn‐containing {K 8 Ce 24 Ge 12 W 120 O 444 (OH) 12 (H 2 O) 64 }, and 30‐Dy‐containing {Dy 30 Co 8 Ge 12 W 108 O 408 (OH) 42 (H 2 O) 30 }, which was reported only recently.…”