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Metal atom lability from a well-defined bimetallic cluster was canvassed as a function of ligand substitution, redox chemistry, and group transfer processes. 

Atomically precise nanoclusters (NCs) provide useful model systems for studying fundamental aspects of the metal-catalysed CO₂reduction reaction (CO₂RR). 

A dipyrrin-supported copper complex mediates C–H bond amination and aziridination of exogenous substrates using electron-deficient arylazides, proceeding through copper-nitrene adducts. 

Despite the myriad Cu-catalyzed nitrene transfer methodologies to form new C–N bonds (e.g.,amination, aziridination), the critical reaction intermediates have largely eluded direct characterization due to their inherent reactivity. Herein, we report the synthesis of dipyrrin-supported Cu nitrenoid adducts, investigate their spectroscopic features, and probe their nitrene transfer chemistry through detailed mechanistic analyses. Treatment of the dipyrrin CuI complexes with substituted organoazides affords terminally ligated organoazide adducts with minimal activation of the azide unit as evidenced by vibrational spectroscopy and single crystal X-ray diffraction. The Cu nitrenoid, with an electronic structure most consistent with a triplet nitrene adduct of CuI, is accessed following geometric rearrangement of the azide adduct from k1-N terminal ligation to k1-N internal ligation with subsequent expulsion of N2. For perfluorinated arylazides, stoichiometric and catalytic C–H amination and aziridination was observed. Mechanistic analysis employing substrate competition reveals an enthalpically-controlled, electrophilic nitrene transfer for primary and secondary C–H bonds. Kinetic analyses for catalytic amination using tetrahydrofuran as a model substrate reveal pseudo-first order kineticsunderrelevantaminationconditionswithafirst-orderdependenceonbothCuandorganoazide. Activation parameters determined from Eyring analysis(DH‡=9.2(2)kcalmol−1,DS‡=−42(2)calmol−1 K−1, DG‡ 298K =21.7(2) kcal mol−1) and parallel kinetic isotope effect measurements (1.10(2)) are consistent with rate-limiting Cu nitrenoid formation, followed by a proposed stepwise hydrogen-atom abstraction and rapid radical recombination to furnish the resulting C–N bond. The proposed mechanism and experimental analysis are further corroborated by density functional theory calculations. Multiconfigurational calculations provide insight into the electronic structure of the catalytically relevant Cu nitrene intermediates. The findings presented herein will assist in the development of future methodology for Cu-mediated C–N bond forming catalysis. 

We report the selective electrochemical biphasic capture of the uranyl cation (UO 2 2+ ) from mixed-metal alkali (Cs + ), lanthanide (Nd 3+ , Sm 3+ ), and actinide (Th 4+ , UO 2 2+ ) aqueous solutions to an organic, 1,2-dichloroethane (DCE), phase using the ortho -substituted nido -carborane anion, [1,2-(Ph 2 PO) 2 -1,2-C 2 B 10 H 10 ] 2− (POCb2−). The reduced POCb2− is generated by electrochemical reduction of the closo -carborane, POCb, prior to mixing with the aqueous mixed-metal solution. Subsequent UO 2 2+ release from the captured product, [UO2(POCb)2]2−, was performed by galvanostatic bulk electrolysis of the DCE phase and back-extraction of UO 2 2+ to a fresh aqueous phase. The selective capture and release of UO 2 2+ was confirmed by combined ICP-OES and NMR spectral analyses of the aqueous and organic phases, respectively, against the newly synthesized nido -carborane complexes, [[CoCp*2][Cs(POCb)]]2, [CoCp*2]3[Nd(POCb)3], [CoCp*2]3[Sm(POCb)3], and [CoCp*2]2[Th(POCb)3].