Self‐Assembly of Hexanuclear Clusters of 4f and 5f Elements with Cation Specificity

Abstract

Six hexanuclear clusters of 4f and 5f elements were synthesized by room‐temperature slow concentration experiments. Cerium(IV), thorium(IV), and plutonium(IV) each form two different hexanuclear clusters, among which the cerium and plutonium clusters are isotypic, whereas the thorium clusters show more diversity. The change in ionic radii of approximately 0.08 Å between these different metal ions tunes the cavity size so that NH4+ (1.48 Å) has the right dimensions to assemble the cerium and plutonium clusters, whereas Cs+ (1.69 Å) is necessary to assemble the thorium clusters. If these cations are not used in the reactions, only amorphous material is obtained.

Ceric Ammonium Nitrate and Ceric Ammonium Chloride as Precursors for Ceric Siloxides: Ammonia and Ammonium Inclusion

“…Further comparison with literature data proved difficult although some cerium compounds with ammonium counterions have been reported. Those comprise several ceric complexes like the acetylacetonate derivative [Ce 2 (1,3‐pdta) 2 (NH 4 ) 2 (H 2 O) 4 ](H 2 O) 8 {H 4 pdta = CH 2 [CH 2 N(CH 2 CO 2 H) 2 ] 2 }, the hexametallic [Ce 6 O 5 (OH) 3 (µ‐C 6 H 5 COO) 9 (NO 3 ) 3 (NH 4 )(DMF) 3 ](DMF)(H 2 O), [(NH 4 ) 6 Ce 6 (NO 3 ) 12 {C 6 H 4 (PO 3 )(PO 3 H)} 6 (H 2 O) 9 ] and [(NH 4 ) 6 Ce 6 (NO 3 ) 12 {C 6 H 4 (PO 3 )(PO 3 H)} 6 (H 2 O) 3 ], as well as the salen derivative [Ce(L) 2 (NH 4 ) 2 ](PF 6 ) 2 {H 2 L = N , N′ ‐bis(2‐oxy‐3‐methoxybenzylidene)‐1,2‐phenylenediamine} . Cerous complexes include β‐diketonates [Ce{( t Bu)COCH 2 CO(CF 3 )} 4 (NH 4 )], and [Ce{EtOCOCH 2 CO(CF 3 )} 4 (NH 4 )], as well as the oxydiacetate complex [Ce{(O 2 CCH 2 ) 2 O} 3 (NH 4 ) 3 ](H 2 O) …”

Extension of the Plutonium Oxide Nanocluster Family to Include {Pu16} and {Pu22}

“…Several tetravalent actinide nanoclusters have been isolated and characterized which contain a variety of capping ligands. Hexanuclear molecular species are particularly prevalent in the literature and are reported for thorium, uranium, neptunium, and plutonium . Some of these hexanuclear species consist of an octahedral core that is stabilized by organic ligands which contain carboxylic acid functional groups.…”

“…Two octahedral units are fused through edge sharing to form {U 10 }, a uranium(IV) molecular species containing 10 metal centers, whereas face sharing of slightly distorted octahedral units leads to the formation of {U 16 } (Figure d) . The observed distortion within {U 16 } may be due to the presence of both U V and U IV centers, though some hexanuclear species have been reported to contain distorted octahedral symmetries and only An IV metal centers …”

Cerium-based metal organic frameworks with UiO-66 architecture: synthesis, properties and redox catalytic activity

“…25 For cerium(IV), the molecular hexanuclear cluster has been previously reported with sulfate, 26 acetylacetonate, 27 benzoate 28 and 1,2-phenyldiphosphonate ions. 29 To the best of our knowledge only one cerium(IV)-based MOF has been reported in recent years, 30 but did not contain this 60 hexanuclear cluster.…”