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[ASAP] Molecular Complexes Featuring Unsupported Dispersion-Enhanced Aluminum–Copper and Gallium–Copper Bonds
[ASAP] Double-Holed Fullerenes
[ASAP] Photochemical Synthesis of a Stable Terminal Uranium(VI) Nitride
Delivery of a Masked Uranium(II) by an Oxide‐Bridged Diuranium(III) Complex
A molecular diuranium(III) oxide was prepared. It undergoes cleavage of one U−O bonding and effects the reductive coupling of pyridine and the two‐electron reduction of bipyridine by delivering a “UII” synthon. These reactions provide a synthetic route to dinuclear UIII/UIII complexes bridged by redox‐active N‐heterocyclic ligands.
Abstract
Oxide is an attractive linker for building polymetallic complexes that provide molecular models for metal oxide activity, but studies of these systems are limited to metals in high oxidation states. Herein, we synthesized and characterized the molecular and electronic structure of diuranium bridged UIII/UIV and UIII/UIII complexes. Reactivity studies of these complexes revealed that the U−O bond is easily broken upon addition of N‐heterocycles resulting in the delivery of a formal equivalent of UIII and UII, respectively, along with the uranium(IV) terminal‐oxo coproduct. In particular, the UIII/UIII oxide complex effects the reductive coupling of pyridine and two‐electron reduction of 4,4′‐bipyridine affording unique examples of diuranium(III) complexes bridged by N‐heterocyclic redox‐active ligands. These results provide insight into the chemistry of low oxidation state metal oxides and demonstrate the use of oxo‐bridged UIII/UIII complexes as a strategy to explore UII reactivity.
The “Hidden” Reductive [2+2+1]‐Cycloaddition Chemistry of 2‐Phosphaethynolate Revealed by Reduction of a Th‐OCP Linkage
A reaction with the overall appearance of (OCP)− concerted cleavage is revealed to proceed through a [2+2+1]‐cycloaddition reaction intermediate, introducing an unprecedented example of (OCP)− cycloaddition under reducing conditions to the established neutral and oxidative cycloaddition classes of (OCP)− reactivity.
Abstract
The reduction chemistry of the newly emerging 2‐phosphaethynolate (OCP)− is not well explored, and many unanswered questions remain about this ligand in this context. We report that reduction of [Th(TrenTIPS)(OCP)] (2, TrenTIPS=[N(CH2CH2NSiPri 3)]3−), with RbC8 via [2+2+1] cycloaddition, produces an unprecedented hexathorium complex [{Th(TrenTIPS)}6(μ‐OC2P3)2(μ‐OC2P3H)2Rb4] (5) featuring four five‐membered [C2P3] phosphorus heterocycles, which can be converted to a rare oxo complex [{Th(TrenTIPS)(μ‐ORb)}2] (6) and the known cyclometallated complex [Th{N(CH2CH2NSiPri 3)2(CH2CH2SiPri 2CHMeCH2)}] (4) by thermolysis; thereby, providing an unprecedented example of reductive cycloaddition reactivity in the chemistry of 2‐phosphaethynolate. This has permitted us to isolate intermediates that might normally remain unseen. We have debunked an erroneous assumption of a concerted fragmentation process for (OCP)−, rather than cycloaddition products that then decompose with [Th(TrenTIPS)O]− essentially acting as a protecting then leaving group. In contrast, when KC8 or CsC8 were used the phosphinidiide C−H bond activation product [{Th(TrenTIPS)}Th{N(CH2CH2NSiPri 3)2[CH2CH2SiPri 2CH(Me)CH2C(O)μ‐P]}] (3) and the oxo complex [{Th(TrenTIPS)(μ‐OCs)}2] (7) were isolated.
Fullerenes as Key Components for Low‐Dimensional (Photo)electrocatalytic Nanohybrid Materials
This Review discusses synthetic approaches to fullerene‐based hybrids with low‐dimensional (LD) materials and their properties. Recent advances in the design of fullerene‐based LD nanomaterials for (photo)electrocatalytic applications are emphasized. The relationship between the electronic structures and the catalytic functions of the heterostructures is addressed to provide an understanding of these emerging materials at the molecular level.
Abstract
An emerging class of heterostructures with unprecedented (photo)electrocatalytic behavior, involving the combination of fullerenes and low‐dimensional (LD) nanohybrids, is currently expanding the field of energy materials. The unique physical and chemical properties of fullerenes have offered new opportunities to tailor both the electronic structures and the catalytic activities of the nanohybrid structures. Here, we comprehensively review the synthetic approaches to prepare fullerene‐based hybrids with LD (0D, 1D, and 2D) materials in addition to their resulting structural and catalytic properties. Recent advances in the design of fullerene‐based LD nanomaterials for (photo)electrocatalytic applications are emphasized. The fundamental relationship between the electronic structures and the catalytic functions of the heterostructures, including the role of the fullerenes, is addressed to provide an in‐depth understanding of these emerging materials at the molecular level.
[ASAP] Tailoring the Interfacial Interactions of van der Waals 1T-MoS2/C60 Heterostructures for High-Performance Hydrogen Evolution Reaction Electrocatalysis
[ASAP] Phosphangulene: A Molecule for All Chemists
Single‐Crystal‐to‐Single‐Crystal Installation of Ln4(OH)4 Cubanes in an Anionic Metallosupramolecular Framework
Soaking crystals of K6[Rh4Zn4O(l‐cysteinate)12] in a lanthanide acetate solution results in the complete exchange of K+ with Ln3+ in a single‐crystal‐to‐single‐crystal process. For late lanthanides (Ln=Gd–Lu), this process afforded a series of lanthanide cubane clusters with a [Lu4(μ3‐OH)4]8+ core, which connect the RhIII 4ZnII 4 complex anions in a 3D MOF structure, showing magnetic cooling and heterogeneous catalytic abilities.
Abstract
Postsynthetic installation of lanthanide cubanes into a metallosupramolecular framework via a single‐crystal‐to‐single‐crystal (SCSC) transformation is presented. Soaking single crystals of K6[Rh4Zn4O(l‐cys)12] (K6[1]; l‐H2cys=l‐cysteine) in a water/ethanol solution containing Ln(OAc)3 (Ln3+=lanthanide ion) results in the exchange of K+ by Ln3+ with retention of the single crystallinity, producing Ln2[1] (2Ln ) and Ln0.33[Ln4(OH)4(OAc)3(H2O)7][1] (3Ln ) for early and late lanthanides, respectively. While the Ln3+ ions in 2Ln exist as disordered aqua species, those in 3Ln form ordered hydroxide‐bridged cubane clusters that connect [1]6− anions in a 3D metal‐organic framework through coordination bonds with carboxylate groups. This study shows the utility of an anionic metallosupramolecular framework with carboxylate groups for the creation of a series of metal cubanes that have great potential for various applications, such as magnetic materials and heterogeneous catalysts.
[ASAP] An Internuclear J-Coupling of 3He Induced by Molecular Confinement
Mechanochemical Synthesis of Corannulene‐Based Curved Nanographenes
Mechanochemistry is demonstrated to be an effective and sustainable synthetic tool in the preparation of curved π‐materials with high electron affinity and a highly reversible nature of the electron‐transfer process.
Abstract
It is shown that corannulene‐based strained π‐surfaces can be obtained through the use of mechanochemical Suzuki and Scholl reactions. Besides being solvent‐free, the mechanochemical synthesis is high‐yielding, fast, and scalable. Therefore, gram‐scale preparation can be carried out in a facile and sustainable manner. The synthesized nanographene structure carries positive (bowl‐like) and negative (saddle‐like) Gaussian curvatures and adopts an overall quasi‐monkey saddle‐type of geometry. In terms of properties, the non‐planar surface exhibits a high electron affinity that was measured by cyclic voltammetry, with electrolysis and in situ UV/vis spectroscopy experiments indicating that the one‐electron reduced state displays a long lifetime in solution. Overall, these results indicate the future potential of mechanochemistry in accessing synthetically challenging and functional curved π‐systems.
Light‐Controlled Regioselective Synthesis of Fullerene Bis‐Adducts
By incorporating azobenzene photochromic units in the double functionalization of [60]fullerene, the regiochemistry of the double cyclopropanation reaction could be controlled by using either the E or the Z isomeric forms of the photoswitch. Once covalently linked to the C60 sphere, the azobenzene unit changes its light‐ and thermally‐induced isomerization properties.
Abstract
Multi‐functionalization and isomer‐purity of fullerenes are crucial tasks for the development of their chemistry in various fields. In both current main approaches—tether‐directed covalent functionalization and supramolecular masks—the control of regioselectivity requires multi‐step synthetic procedures to prepare the desired tether or mask. Herein, we describe light‐responsive tethers, containing an azobenzene photoswitch and two malonate groups, in the double cyclopropanation of [60]fullerene. The formation of the bis‐adducts and their spectroscopic and photochemical properties, as well as the effect of azobenzene photoswitching on the regiochemistry of the bis‐addition, have been studied. The behavior of the tethers depends on the geometry of the connection between the photoactive core and the malonate moieties. One tether lead to a strikingly different adduct distribution for the E and Z isomers, indicating that the covalent bis‐functionalization of C60 can be controlled by light.
[ASAP] Precise Dimerization of Hollow Fullerene Compartments
Synergy of Electrostatic and π–π Interactions in the Realization of Nanoscale Artificial Photosynthetic Model Systems
The synergy between different non‐covalent interactions is modulated to achieve supramolecular hybrids as electron donor‐acceptor photoactive systems consisting of a tetracationic zinc(II) phthalocyanine and anionic water‐soluble fullerenes. In the resulting monocrystalline assemblies, all the fundamental processes of natural photosynthesis are operative and give rise to highly efficient artificial photosynthetic systems.
Abstract
In the scientific race to build up photoactive electron donor‐acceptor systems with increasing efficiencies, little is known about the interplay of their building blocks when integrated into supramolecular nanoscale arrays, particularly in aqueous environments. Here, we describe an aqueous donor‐acceptor ensemble whose emergence as a nanoscale material renders it remarkably stable and efficient. We have focused on a tetracationic zinc phthalocyanine (ZnPc) featuring pyrenes, which shows an unprecedented mode of aggregation, driven by subtle cooperation between electrostatic and π–π interactions. Our studies demonstrate monocrystalline growth in solution and a symmetry‐breaking intermolecular charge transfer between adjacent ZnPcs upon photoexcitation. Immobilizing a negatively charged fullerene (C60) as electron acceptor onto the monocrystalline ZnPc assemblies was found to enhance the overall stability, and to suppress the energy‐wasting charge recombination found in the absence of C60. Overall, the resulting artificial photosynthetic model system exhibits a high degree of preorganization, which facilitates efficient charge separation and subsequent charge transport.
[ASAP] Complete Dynamic Reconstruction of C60, C70, and (C59N)2 Encapsulation into an Adaptable Supramolecular Nanocapsule
[ASAP] Fullertubes: Cylindrical Carbon with Half-Fullerene End-Caps and Tubular Graphene Belts, Their Chemical Enrichment, Crystallography of Pristine C90-D5h(1) and C100-D5d(1) Fullertubes, and Isolation of C108, C120, C132, and C156 Cages of Unknown Structures
[ASAP] Self-Associating Curved π-Electronic Systems with Electron-Donating and Hydrogen-Bonding Properties
[ASAP] Dinitrogen Cleavage by a Heterometallic Cluster Featuring Multiple Uranium–Rhodium Bonds
[ASAP] Correction to “Diuranium(IV) Carbide Cluster U2C2 Stabilized Inside Fullerene Cages”
[ASAP] Inorganic Approach to Stabilizing Nanoscale Toroidicity in a Tetraicosanuclear Fe18Dy6 Single Molecule Magnet
[ASAP] Controlling Defect-State Photophysics in Covalently Functionalized Single-Walled Carbon Nanotubes
[ASAP] Carbon Nanotube Photoluminescence Modulation by Local Chemical and Supramolecular Chemical Functionalization
[ASAP] Facile Oxide to Chalcogenide Conversion for Actinides Using the Boron–Chalcogen Mixture Method
as-Indaceno[3,2,1,8,7,6-ghijklm]terrylene as a near-infrared absorbing C70-fragment
Nature Communications, Published online: 03 August 2020; doi:10.1038/s41467-020-17684-6
The synthesis of hydrocarbons with attractive electronic structures remains challenging. Here, the authors describe the synthesis and properties of the C70 fragment as-indaceno[3,2,1,8,7,6-ghijklm]terrylene, which exhibits near-infrared (NIR) absorption.Nanoscale mechanism of UO2 formation through uranium reduction by magnetite
Nature Communications, Published online: 10 August 2020; doi:10.1038/s41467-020-17795-0
In anoxic environments, soluble hexavalent uranium is reduced and immobilized, however, the underlying molecular-scale reduction mechanism remains unknown. Here, the authors find that U reduction can occur on the surface of magnetite via transient U nanowire structures which collapse into ordered UO2 nanoclusters, which may have implications for understanding nuclear waste evolution and remediation of uranium contamination.Light‐Controlled Regioselective Synthesis of Fullerene Bis‐Adducts
By incorporating azobenzene photochromic units in the double functionalization of [60]fullerene, the regiochemistry of the double cyclopropanation reaction could be controlled by using either the E or the Z isomeric forms of the photoswitch. Once covalently linked to the C60 sphere, the azobenzene unit changes its light‐ and thermally‐induced isomerization properties.
Abstract
Multi‐functionalization and isomer‐purity of fullerenes are crucial tasks for the development of their chemistry in various fields. In both current main approaches—tether‐directed covalent functionalization and supramolecular masks—the control of regioselectivity requires multi‐step synthetic procedures to prepare the desired tether or mask. Herein, we describe light‐responsive tethers, containing an azobenzene photoswitch and two malonate groups, in the double cyclopropanation of [60]fullerene. The formation of the bis‐adducts and their spectroscopic and photochemical properties, as well as the effect of azobenzene photoswitching on the regiochemistry of the bis‐addition, have been studied. The behavior of the tethers depends on the geometry of the connection between the photoactive core and the malonate moieties. One tether lead to a strikingly different adduct distribution for the E and Z isomers, indicating that the covalent bis‐functionalization of C60 can be controlled by light.
Quantification of the Magnetic Anisotropy of a Single‐Molecule Magnet from the Experimental Electron Density
The experimental electron density obtained from 20 K synchrotron X‐ray diffraction data was used here to quantify the zero‐field splitting parameter in a CoII‐based single‐molecule magnet. The methodology uses the d‐orbital populations to derive the ground‐state wavefunction composition, which is shown to be strongly correlated to the zero‐field splitting.
Abstract
Reported here is an entirely new application of experimental electron density (EED) in the study of magnetic anisotropy of single‐molecule magnets (SMMs). Among those SMMs based on one single transition metal, tetrahedral CoII‐complexes are prominent, and their large zero‐field splitting arises exclusively from coupling between the d and dxy orbitals. Using very low temperature single‐crystal synchrotron X‐ray diffraction data, an accurate electron density (ED) was obtained for a prototypical SMM, and the experimental d‐orbital populations were used to quantify the dxy‐d coupling, which simultaneously provides the composition of the ground‐state Kramers doublet wave function. Based on this experimentally determined wave function, an energy barrier for magnetic relaxation in the range 193–268 cm−1 was calculated, and is in full accordance with the previously published value of 230 cm−1 obtained from near‐infrared spectroscopy. These results provide the first clear and direct link between ED and molecular magnetic properties.
Spin Ice‐like Magnetic Relaxation of a Two‐dimensional Network based on Manganese(III) Salen‐type Single‐Molecule Magnets
Spin ice‐like magnetic relaxation was found in a two‐dimensional network of MnIII salen‐type single‐molecule magnets with S T=4. The spin ice‐like behavior was a consequence of the competition between the ferromagnetic interaction and local noncollinear magnetic anisotropies on the single‐molecule magnets.
Abstract
Spin ice is an exotic type of magnetism displayed by bulk rare‐earth pyrochlore oxides. We discovered a spin ice‐like magnetic relaxation of [{Mn(saltmen)}4{Mn(CN)6}](ClO4)⋅13 H2O (saltmen2−=N,N′‐(1,1,2,2‐tetramethylethylene)bis(salicylideneiminate)). This magnetic system can be considered as a two‐dimensional network of MnIII salen‐type single‐molecule magnets (SMMs) in which each SMM unit (ST=4) has two orthogonally oriented axial anisotropies and is connected ferromagnetically through the [Mn(CN)6]3− unit (S=1). This work illustrates that a two‐dimensional SMM network with competition between the ferromagnetic interaction and local noncollinear magnetic anisotropies on SMMs is a new type of magnetic system exhibiting slow relaxation of magnetization with a Davidson‐Cole‐type broad distribution of the relaxation time.
[ASAP] Unprecedented Radiation Resistant Thorium–Binaphthol Metal–Organic Framework
Stable Actinide π Complexes of a Neutral 1,4‐Diborabenzene
Boracycles π‐captured : The first actinide‐based molecules featuring π‐ligated neutral diborabenzene (dbb) as sandwich‐type ligand are reported. Experimental and theoretical studies suggest that the unique strength of the actinide–dbb bond is mainly electrostatic in nature with distinct covalent ligand‐to‐metal orbital contributions.
Abstract
The π coordination of arene and anionic heteroarene ligands is a ubiquitous bonding motif in the organometallic chemistry of d‐block and f‐block elements. By contrast, related π interactions of neutral heteroarenes including neutral bora‐π‐aromatics are less prevalent particularly for the f‐block, due to less effective metal‐to‐ligand backbonding. In fact, π complexes with neutral heteroarene ligands are essentially unknown for the actinides. We have now overcome these limitations by exploiting the exceptionally strong π donor capabilities of a neutral 1,4‐diborabenzene. A series of remarkably robust, π‐coordinated thorium(IV) and uranium(IV) half‐sandwich complexes were synthesized by simply combining the bora‐π‐aromatic with ThCl4(dme)2 or UCl4, representing the first examples of actinide complexes with a neutral boracycle as sandwich‐type ligand. Experimental and computational studies showed that the strong actinide–heteroarene interactions are predominately electrostatic in nature with distinct ligand‐to‐metal π donation and without significant π/δ backbonding contributions.