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Despite their connection to ammonia synthesis, little is known about the ability of iron-bound, bridging nitrides to form N-H bonds. Herein we report a linear diiron bridging nitride complex supported by a redox-active macrocycle. The unique ability of the ligand scaffold to adapt to the geometric preference of the bridging species was found to facilitate the formation of N-H bonds via proton-coupled electron transfer to generate a μ-amide product. The structurally analogous μ-silyl- and μ-borylamide complexes were shown to form from the net insertion of the nitride into the E-H bonds (E=B, Si). Protonation of the parent bridging amide produced ammonia in high yield, and treatment of the nitride with PhSH was found to liberate NH 3 in high yield through a reaction that engages the redox-activity of the ligand during PCET., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The separation of rare-earth ions from one another is challenging due to their chemical and physical similarities. Nearly all rare-earth separations rely upon small changes in ionic radii to direct speciation or reactivity. Herein, we show that the intrinsic magnetic properties of the rare-earth ions impact the separations of light/heavy and selected heavy/heavy binary mixtures. Using TriNOx 3- ([{(2- t BuNO)C 6 H 4 CH 2 } 3 N] 3- ) rare-earth complexes, we efficiently and selectively crystallized heavy rare earths (Tb-Yb) from a mixture with light rare earths (La and Nd) in the presence of an external Fe 14 Nd 2 B magnet, concomitant with the introduction of a concentration gradient (decrease in temperature). The optimal separation was observed for an equimolar mixture of La:Dy, which gave an enrichment factor of EF La:Dy =297±31 for the solid fraction, compared to EF La:Dy =159±22 in the absence of the field, and achieving a 99.7 % pure Dy sample in one step. These results indicate that the application of a magnetic field can improve performance in a molecular separation system for paramagnetic rare-earth cations., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Incorporation of photoresponsive molecules within soft materials can provide spatiotemporal control over bulk properties and address challenges in targeted delivery and mechanical variability. However, the kinetics of in situ photochemical reactions are often slow and typically employ ultraviolet wavelengths. Here, we present a novel photoactive crosslinker Ru(bipyridine) 2 (3-pyridinaldehyde) 2 (RuAldehyde), which was reacted with hydrazide-functionalized hyaluronic acid to form hydrogels capable of encapsulating protein cargo. Visible light irradiation (400-500 nm) initiated rapid ligand exchange on the ruthenium center, which degraded the hydrogel within seconds to minutes, depending on gel thickness. An exemplar enzyme cargo, TEM1 β-lactamase, was loaded into and photoreleased from the Ru-hydrogel. To expand their applications, Ru-hydrogels were also processed into microgels using a microfluidic platform., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The first example of the OCPPCO ligand, diisophosphaethynolate, is reported via reductive coupling of a Sc-OCP precursor. Upon reduction with KC 8 , isolation of the dinuclear complex, namely [K(OEt 2 )] 2 [(nacnac)Sc(OAr)] 2 (OCPPCO), is observed, leading to a unique motif [OCPPCO] 4- , stabilized by two scandium centers. Detailed NMR spectra of all complexes as well as IR and single crystal X-ray studies were obtained to fully elucidate the nature of these complexes in solution as well as in the solid state. Theory is combined to probe the electronic structure and orbitals responsible for the bonding interactions in the Sc-OCPPCO-Sc skeleton but also to compare to the linear mode observed in the precursor., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Methyl benzoate, N,N-dimethylbenzamide, and benzophenone were reduced by U III [N(SiMe 3 ) 2 ] 3 resulting in uranium(IV) products. Reduction of benzophenone lead to U IV [OC⋅Ph 2 )][N(SiMe 3 ) 2 ] 3 , (1.1) which forms the dinuclear complex, [N(SiMe 3 ) 2 ] 3 U IV (OCPhPh-CPh 2 O)U IV [N(SiMe 3 ) 2 ] 3 (1.2), through coupling of the ketyl radical species upon crystallization. Reaction of N,N-dimethylbenzamide with U III [N(SiMe 3 ) 2 ] 3 resulted in U IV [OC⋅(Ph)(NMe 2 )][N(SiMe 3 ) 2 ] 3 (2), a uranium(IV) compound and the first example of a charge-separated amide radical. In the case of methyl benzoate, the reduction resulted in U IV (OMe)[N(SiMe 3 ) 2 ] 3 (3) and benzaldehyde as the reduced organic fragment. Compound 2 showed the ability to act as a uranium(III) synthon in its reactivity with trimethylsilyl azide, a reaction that yielded U V (=NSiMe 3 )[N(SiMe 3 ) 2 ] 3 . Additionally, 2 was reduced with potassium graphite resulting in [U(μ-O)[O=C(NMe 2 )(Ph)][N(SiMe 3 ) 2 ] 2 ] 2 (4), a dinuclear uranium compound bridged by oxo ligands. Reduction of 2 in the presence of 15-crown-5 afforded isolation of the mono-oxo compound, [(15-crown-5) 2 K][UO[N(SiMe 3 ) 2 ] 3 ] (5). The results expand the reduction capabilities of U III complexes and demonstrate a strategy for isolating novel metal-stabilized radicals., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Synthetic methods for the coordination of the monoanionic bis[2-(diisopropylphosphino)-4-methylphenyl]amido (PNP) ligand framework to the cerium(III) cation have been developed and applied for the isolation of a series of {(PNP)Ce} and {(PNP) 2 Ce} type complexes. The structures of the complexes were studied by X-ray diffraction and multinuclear NMR spectroscopy. We found that the cerium(III) ion can induce the elimination of one of the iPr groups at phosphorus to yield a new dianionic PNP tridentate framework (PNP -iPr ) featuring a phosphido-donor functionality, which is bound to the cerium ion with the shortest known Ce-P bond of 2.7884(14) Å for molecular compounds. The reaction of the complex [(PNP)Ce{N(SiMe 3 ) 2 } 2 ] (1) with Ph 2 CO gave the Ce-bound product of C-C coupling, - N(SiMe 3 )SiMe 2 CH 2 -CPh 2 O - , through the C-H bond activation of a SiMe 3 group. 31 P NMR spectroscopy was used to estimate the presence of a vacant coordination position at the cerium ion in the Ce III -PNP complexes by the examination of the δ( 31 P) shift recorded both in non-polar (C 6 D 6 ) and polar ([D 8 ]THF) solvents. Moreover, 31 P NMR spectroscopy was also found to be a useful tool for the estimation of the Ce-P bond distances in {(PNP)Ce III } and {(PNP) 2 Ce III } systems. Electrochemical and computational studies for 1 and its lanthanum analogue containing a redox-innocent metal center revealed the stabilization of the Ce III oxidation state by the PNP ligand., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Dicobalt complexes supported by flexible macrocyclic ligands were used to target the generation of the bridging nitrido species [( n PDI 2 )Co 2 (μ-N)(PMe 3 ) 2 ] 3+ (PDI=2,6-pyridyldiimine; n=2, 3, corresponding to the number of catenated methylene units between imino nitrogen atoms). Depending on the size of the macrocycle and the reaction conditions (solution versus solid-state), the thermolysis of azide precursors yielded bridging phosphinimido [( 2 PDI 2 )Co 2 (μ-NPMe 3 )(PMe 3 ) 2 ] 3+ , amido [( n PDI 2 )Co 2 (μ-NH 2 )(PMe 3 ) 2 ] 3+ (n=2, 3), and C-H amination [( 3 PDI 2 *-μ-NH)Co 2 (PMe 3 ) 2 ] 3+ products. All results are consistent with the initial formation of [( n PDI 2 )Co 2 (μ-N)(PMe 3 ) 2 ] 3+ , followed by 1) PMe 3 attack on the nitride, 2) net hydrogen-atom transfer to form N-H bonds, or 3) C-H amination of the alkyl linker of the n PDI 2 ligand., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Purification of rare earth elements is challenging due to their chemical similarities. All of the deployed separation methods rely on thermodynamic properties, such as distribution equilibria in solvent extraction. Rare-earth-metal separations based on kinetic differences have not been examined. Herein, we demonstrate a new approach for rare-earth-element separations by exploiting differences in the oxidation rates within a series of rare earth compounds containing the redox-active ligand [{2-(tBuN(O))C 6 H 4 CH 2 } 3 N] 3- . Using this method, a single-step separation factor up to 261 was obtained for the separation of a 50:50 yttrium-lutetium mixture., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The complex [(nacnac)Ti(OAr)] 2 (μ 2 :η 2 ,η 2 -P 2 ) (1) is formed via reductive decarbonylation of the phosphaethynolate ion - [OCP], which serves as a P atom source. Complex 1 is the first structurally characterized Group 4 transition metal P 2 complex and its structure reveals the rhombic Ti 2 P 2 core is essentially planar with short bond lengths suggesting some degree of multiple bonding character between the Ti-P and P-P sites. Computational studies of 1 provide an understanding of the Ti 2 P 2 core as well as the origin of the highly downfield 31 P NMR spectroscopic signal., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Nuclear inelastic scattering of (57)Fe labeled [NiFe] hydrogenase is shown to give information on different states of the enzyme. It was thus possible to detect and assign Fe-CO and Fe-CN bending and stretching vibrations of the active site outside the spectral range of the Fe-S cluster normal modes., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)