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Although synthesis, reactivity, and bonding of U(IV) and Th(IV) complexes have been extensively studied, direct comparison of fully analogous compounds is rare. Herein, we report corresponding complexes 1-U and 1-Th , in which U(IV) and Th(IV) are supported by the tetradentate pyridine-decorated dianionic ligand N 2 NN' (1,1,1-trimethyl- N -(2-(((pyridin-2-ylmethyl)(2-((trimethylsilyl)amino)benzyl)amino)methyl)phenyl)silanamine). Although 1-U and 1-Th are structurally very similar, they display disparate reactivities with TMS 3 SiK (tris(trimethylsilyl)silylpotassium). The reaction of (N 2 NN')UCl 2 ( 1-U ) and 1 equiv of TMS 3 SiK in THF unexpectedly formed [Cl(N 2 NN')U] 2 O ( 2-U ) featuring an unusual bent U-O-U moiety. In contrast, a salt elimination reaction between (N 2 NN')ThCl 2 ( 1-Th ) and 1 equiv of TMS 3 SiK led to thorium complex 2-Th , in which the pyridyl group has undergone a 1,4-addition nucleophilic attack. Complex 2-Th serves as a synthon for preparing dimetallic bis-azide complex 3-Th by reaction with NaN 3 . The complexes were characterized by X-ray crystal diffraction, solution NMR, FT-IR, and elemental analysis. Computations of the formation mechanism of 2-U from 1-U suggest reduced U(III) as a key intermediate for promoting the cleavage of the C-O bonds of THF. The inaccessible nature of Th(III) as an intermediate oxidation state explains the very different reactivity of 1-Th versus 1-U . Given that reactants 1-U and 1-Th and products 2-U and 2-Th all comprise tetravalent actinides, this is an unusual case of very disparate reactivity despite no net change in the oxidation state. Complexes 2-U and 3-Th provide a basis for the synthesis of other dinuclear actinide complexes with novel reactivity and properties.

Herein we present a new metalloligand, Th 6 L 12 [IHEP-10; L = 4-pyrazolecarboxylic acid (H 2 PyC)], which can be used to generate a novel multicomponent heterometallic metal-organic framework (MOF), [[Cu 3 (μ 3 -OH)(NO 3 )(H 2 O) 2 ] 2 Th 6 (μ 3 -O) 4 (μ 3 -OH) 4 (PyC) 6 (HPyC) 6 (H 2 O) 6 ](NO 3 ) 2 (IHEP-11), through further assembly with second [Cu 3 (μ 3 -OH)(PyC) 3 ] clusters. In IHEP-11, six Cu 3 clusters are connected by six NO 3 - anions to form an unprecedented annular Cu 18 cluster, which can be viewed as a 12-connected node to link with 12 Th 6 clusters, resulting a 4,12-connected shp net. Benefiting from the cationic framework and 3D porous structure, IHEP-11 can efficiently remove ReO 4 - (an analogue of radioactive 99 TcO 4 - ) from aqueous solution in a wide pH range. This work highlights the feasibility of constructing multicomponent MOFs through a step-by-step synthesis strategy based on metalloligands.