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A series of mono‐ and di‐nuclear AgI complexes supported by a flexible macrocyclic ligand are reported. The geometric flexibility of the ligand was found to allow for a range of Ag−Ag interactions in the disilver complexes, depending on the identities of both the ancillary ligand and the counterion. Studies of the solution‐phase dynamic exchange processes for these latter complexes found rapid interconversion through a mechanism that retained the multi‐nuclearity. Quantum Theory of Atoms in Molecules (QTAIM) and Independent Gradient Model based on Hirshfeld partition (IGMH) analyses are used to evaluate the d10‐d10 interactions between silver centers in the various geometries observed for the solid‐state structures of these complexes, revealing nearly identical Ag−Ag interactions, regardless of the relative geometries of the Ag centers. Instead, a weak, but non‐negligible, inter‐ligand interaction between two isocyanide units may contribute to the folded‐ligand geometry observed in the solid state. [ABSTRACT FROM AUTHOR]

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 NH3 in high yield through a reaction that engages the redox‐activity of the ligand during PCET. [ABSTRACT FROM AUTHOR]

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 TriNOx3− ([{(2‐tBuNO)C6H4CH2}3N]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 Fe14Nd2B 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 EFLa:Dy=297±31 for the solid fraction, compared to EFLa: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. [ABSTRACT FROM AUTHOR]

Abstract: 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. [ABSTRACT FROM AUTHOR]

Abstract: The first example of the OCPPCO ligand, diisophosphaethynolate, is reported via reductive coupling of a Sc−OCP precursor. Upon reduction with KC8, isolation of the dinuclear complex, namely [K(OEt2)]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. [ABSTRACT FROM AUTHOR]

Abstract: The first example of the OCPPCO ligand, diisophosphaethynolate, is reported via reductive coupling of a Sc−OCP precursor. Upon reduction with KC8, isolation of the dinuclear complex, namely [K(OEt2)]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. [ABSTRACT FROM AUTHOR]

Abstract: The first example of the OCPPCO ligand, diisophosphaethynolate, is reported via reductive coupling of a Sc−OCP precursor. Upon reduction with KC8, isolation of the dinuclear complex, namely [K(OEt2)]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. [ABSTRACT FROM AUTHOR]

Abstract: The first example of the OCPPCO ligand, diisophosphaethynolate, is reported via reductive coupling of a Sc−OCP precursor. Upon reduction with KC8, isolation of the dinuclear complex, namely [K(OEt2)]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. [ABSTRACT FROM AUTHOR]

Methyl benzoate, N,N-dimethylbenzamide, and benzophenone were reduced by UIII[N(SiMe3)2]3 resulting in uranium(IV) products. Reduction of benzophenone lead to UIV[OC·Ph2)][N(SiMe3)2]3, (1.1) which forms the dinuclear complex, [N(SiMe3)2]3UIV(OCPhPh-CPh2O)UIV[N(SiMe3)2]3 (1.2), through coupling of the ketyl radical species upon crystallization. Reaction of N,N-dimethylbenzamide with UIII[N(SiMe3)2]3 resulted in UIV[OC·(Ph)(NMe2)][N(SiMe3)2]3 (2), a uranium(IV) compound and the first example of a chargeseparated amide radical. In the case of methyl benzoate, the reduction resulted in UIV(OMe)[N(SiMe3)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 UV(= NSiMe3)[N(SiMe3)2]3. Additionally, 2 was reduced with potassium graphite resulting in [U(μ-O)[O=C(NMe2)(Ph)] [N(SiMe3)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)2K][UO[N(SiMe3)2]3] (5). The results expand the reduction capabilities of UIII complexes and demonstrate a strategy for isolating novel metal-stabilized radicals. [ABSTRACT FROM AUTHOR]

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)2Ce} 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(SiMe3)2}2] ( 1) with Ph2CO gave the Ce-bound product of C−C coupling, -N(SiMe3)SiMe2CH2-CPh2O−, through the C−H bond activation of a SiMe3 group. 31P NMR spectroscopy was used to estimate the presence of a vacant coordination position at the cerium ion in the CeIII-PNP complexes by the examination of the δ(31P) shift recorded both in non-polar (C6D6) and polar ([D8]THF) solvents. Moreover, 31P NMR spectroscopy was also found to be a useful tool for the estimation of the Ce−P bond distances in {(PNP)CeIII} and {(PNP)2CeIII} systems. Electrochemical and computational studies for 1 and its lanthanum analogue containing a redox-innocent metal center revealed the stabilization of the CeIII oxidation state by the PNP ligand. [ABSTRACT FROM AUTHOR]

Dicobalt complexes supported by flexible macrocyclic ligands were used to target the generation of the bridging nitrido species [( nPDI2)Co2(μ-N)(PMe3)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 [(2PDI2)Co2(μ-NPMe3)(PMe3)2]3+, amido [( nPDI2)Co2(μ-NH2)(PMe3)2]3+ ( n=2, 3), and C−H amination [(3PDI2*-μ-NH)Co2(PMe3)2]3+ products. All results are consistent with the initial formation of [( nPDI2)Co2(μ-N)(PMe3)2]3+, followed by 1) PMe3 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 nPDI2 ligand. [ABSTRACT FROM AUTHOR]

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))C6H4CH2}3N]3−. Using this method, a single-step separation factor up to 261 was obtained for the separation of a 50:50 yttrium-lutetium mixture. [ABSTRACT FROM AUTHOR]

The complex [(nacnac)Ti(OAr)]2(μ2:η2,η2-P2) ( 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 P2 complex and its structure reveals the rhombic Ti2P2 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 Ti2P2 core as well as the origin of the highly downfield 31P NMR spectroscopic signal. [ABSTRACT FROM AUTHOR]

Nuclear inelastic scattering of 57Fe 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. [ABSTRACT FROM AUTHOR]

Blick ins Zentrum: Die Methode der inelastischen kernresonanten Streuung (NRVS) wurde genutzt, um 57Fe ‐ markierte [NiFe] ‐ Hydrogenase in unterschiedlichen Zuständen des Enzyms zu untersuchen. Damit gelang es, die Fe ‐ CO ‐ und Fe ‐ CN ‐ Beuge ‐ und ‐ Streckschwingung außerhalb des Spektralbereichs der Normalmoden der Fe ‐ S ‐ Cluster zu detektieren und zuzuordnen (siehe Spektrum). [ABSTRACT FROM AUTHOR]

The coordination chemistry of complexes featuring a PNP ligand framework and the redox active lanthanide ion, cerium(III), was initiated. The cerium(III) ion induced the transformation of one of the phosphino donor arms at a parent PNP ligand into a new phosphido functionality. The Ce−PNP systems were also employed for C−C bond‐forming reactions and the molecular structures of Ce−PNP complexes were studied both in solution and in the solid state. More information can be found in the Full Paper by O. V. Ozerov, E. J. Schelter et al. on page 17923. [ABSTRACT FROM AUTHOR]

The active site of [NiFe] hydrogenase is an excellent catalyst for hydrogen conversion with an intriguing ability to recover from exposure to dioxygen. In their Communication on page 724 ff., W. Lubitz, S. P. Cramer, and co‐workers use the synchrotron technique of nuclear resonance vibrational spectroscopy to identify normal modes associated with active‐site FeCN and FeCO motion. [ABSTRACT FROM AUTHOR]

Das aktive Zentrum der [NiFe] ‐ Hydrogenase ist ein exzellenter Katalysator der Wasserstoffumsetzung mit der faszinierenden Fähigkeit, sich nach Sauerstoffexposition zurückzubilden. W. Lubitz, S. P. Cramer et al. nutzen in ihrer Zuschrift auf S. 752 ff. die Synchrotrontechnik der kernresonanten inelastischen Streuung, um Normalmoden der Fe ‐ CN ‐ und Fe ‐ CO ‐ Bewegung im aktiven Zentrum zu identifizieren. [ABSTRACT FROM AUTHOR]