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Thorium Oxo‐Clusters as Building Blocks for Open Frameworks
Author(s) -
Falaise Clément,
Kozma Karoly,
Nyman May
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201802671
Subject(s) - chemistry , tetramethylammonium , monomer , thorium , crystallography , actinide , polymerization , aqueous solution , ligand (biochemistry) , random hexamer , sulfate , inorganic chemistry , ion , materials science , polymer , organic chemistry , biochemistry , receptor , uranium , metallurgy
Abstract Fundamental understanding of tetravalent actinide chemistry is essential to optimize many steps of the nuclear fuel cycle, as well as to predict actinide speciation in the environment. Herein, we report synthesis and structure of three open inorganic frameworks composed of Th 4+ ‐oligomers and sulfate anions. The compounds [Th 10 O 4 (OH) 8 (SO 4 ) 12 (H 2 O) 18 ] ⋅ 28 H 2 O ( 1 ), [Th 9 O 4 (OH) 5 (SO 4 ) 12 (H 2 O) 18 ] ⋅ 1 TMA ⋅ 18 H 2 O ( 2 ), and [Th 8.5 O 4 (OH) 4 (SO 4 ) 12 (H 2 O) 18 ] ⋅ 2 TMA ⋅ n H 2 O ( 3 ) were obtained by slow evaporation of aqueous Th 4+ ‐SO 4 2− solutions, with variable SO 4 2− :Th 4+ ratios (SO 4 2− :Th 4+ =1:1, 1.5:1 and 2:1 for 1 , 2 , and 3 ; TMA=tetramethylammonium). The structure of 1 features a neutral open framework architecture with two interpenetrating networks, built from Th 6 O 4 (OH) 4 12+ hexamers and Th 2 (OH) 2 6+ dimers, linked by sulfate anions. The complex anionic framework of 2 is built from hexamers, dimers, and monomers, with charge‐balancing TMA cations. Compound 3 is very similar to 2 , but it is constructed only from hexamers and monomers. Small angle X‐ray scattering (SAXS) of the reaction solutions reveals pre‐assembled hexamer building units in the presence of sulfate, and underlines the key role of the sulfate‐oxoanion ligand on thorium polymerization processes.