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A single-source-precursor approach was developed to synthesize uranium-based materials outside of the typically-studied oxides. This approach allows for shorter reaction times, milder reaction conditions, and control over the chemicals present in synthesis. To this end, the first homoleptic uranium thioamidate complex was synthesized as a precursor for US 2 materials. Pyrolysis of the thioamidate results in decomposition via an alkene elimination pathway and formation of γ-US 2 , which has historically been hard to access without the need for a secondary sulfur source. Despite the oxophilicity of uranium, the method successfully forms US 2 without the inclusion of oxygen in the bulk final product. These findings are supported by simultaneous thermal analysis, elemental analysis, powder X-ray diffraction, and uranium L 3 -edge X-ray absorption fine-structure spectroscopy. This work represents the first example of a single-source precursor approach to target and synthesize actinide materials other than the oxides., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Reaction of the potassium pentamethylcyclopentadienyl iridate tris-hydride K[IrCp*H 3 ] with UCl 4 and ThCl 4 (DME) 2 led to the complete replacement of the halide ligands to generate multimetallic complexes U{(μ-H) 3 IrCp*} 4 (1) and Th{[(μ-H 2 )(H)IrCp*] 2 [(μ-H) 3 IrCp*] 2 } (2), respectively. These analogues feature a significant discrepancy in hydride bonding modes; 1 contains twelve bridging hydrides while 2 contains ten bridging hydrides and two terminal, Ir-bound hydrides. Use of a U(iii) starting material, UI 3 (1,4-dioxane) 1.5 , resulted in the octanuclear complex {U[(μ 2 -H 3 )IrCp*] 2 [(μ 3 -H 2 )IrCp*]} 2 (3). Computational studies indicate significant bonding character between U/Th and Ir in 1 and 2, with f-orbital involvement in the singly-occupied molecular orbitals of the uranium species 1. In addition, these studies attribute the variation in hydride bonding between 1 and 2 to differences in dispersion effects., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A new, air-stable, permanently porous uranium(iv) metal-organic framework U(bdc) 2 ( 1 , bdc 2- = 1,4-benzenedicarboxylate) was synthesized and its H 2 and CH 4 adsorption properties were investigated. Low temperature adsorption isotherms confirm strong adsorption of both gases in the framework at low pressures. In situ gas-dosed neutron diffraction experiments with different D 2 loadings revealed a rare example of cooperative framework contraction (Δ V = -7.8%), triggered by D 2 adsorption at low pressures. This deformation creates two optimized binding pockets for hydrogen ( Q st = -8.6 kJ mol -1 ) per pore, in agreement with H 2 adsorption data. Analogous experiments with CD 4 ( Q st = -24.8 kJ mol -1 ) and N , N -dimethylformamide as guests revealed that the binding pockets in 1 adjust by selective framework contractions that are unique for each adsorbent, augmenting individual host-guest interactions. Our results suggest that the strategic combination of binding pockets and structural flexibility in metal-organic frameworks holds great potential for the development of new adsorbents with an enhanced substrate affinity., (This journal is © The Royal Society of Chemistry 2020.)

Rare earth (RE) metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare REs. To incentivize recycling, there is a clear need for the development of simple methods for targeted separations of mixtures of RE metal salts. Metal complexes of a tripodal hydroxylaminato ligand, TriNOx 3- , featured a size-sensitive aperture formed of its three η 2 -(N,O) ligand arms. Exposure of cations in the aperture induced a self-associative equilibrium comprising RE(TriNOx)THF and [RE(TriNOx)] 2 species. Differences in the equilibrium constants K dimer for early and late metals enabled simple separations through leaching. Separations were performed on RE1/RE2 mixtures, where RE1 = La-Sm and RE2 = Gd-Lu, with emphasis on Eu/Y separations for potential applications in the recycling of phosphor waste from compact fluorescent light bulbs. Using the leaching method, separations factors approaching 2,000 were obtained for early-late RE combinations. Following solvent optimization, >95% pure samples of Eu were obtained with a 67% recovery for the technologically relevant Eu/Y separation., Competing Interests: The authors declare the following competing financial interest: Intellectual property pertaining to the technology described in this article is covered by International Patent Application no. PCT/US2015/042703.

N-tert-butyl-N-2-pyridylhydroxylamines were synthesized from 2-halopyridines and 2-methyl-2-nitrosopropane using magnesium-halogen exchange. The use of Turbo Grignard generated the metallo-2-pyridyl intermediate more reliably than alkyllithium reagents. The hydroxylamines were characterized using NMR, electrochemistry, and density functional theory. Substitution of the pyridyl ring in the 3-, 4-, and 5-positions was used to vary the potential of the nitroxyl/oxoammonium redox couple by 0.95 V. DFT computations of the electrochemical properties agree with experiment and provide a toolset for the predictive design of pyridyl nitroxides.