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  1. Abstract

    Vacancy‐ordered double perovskites are attracting significant attention due to their chemical diversity and interesting optoelectronic properties. With a view to understanding both the optical and magnetic properties of these compounds, two series of RuIVhalides are presented;A2RuCl6andA2RuBr6, whereAis K, NH4, Rb or Cs. We show that the optical properties and spin‐orbit coupling (SOC) behavior can be tuned through changing theAcation and the halide. Within a series, the energy of the ligand‐to‐metal charge transfer increases as the unit cell expands with the largerAcation, and the band gaps are higher for the respective chlorides than for the bromides. The magnetic moments of the systems are temperature dependent due to a non‐magnetic ground state withJeff=0 caused by SOC. Ru‐Xcovalency, and consequently, the delocalization of metald‐electrons, result in systematic trends of the SOC constants due to variations in theAcation and the halide anion.

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  2. Methods for the straightforward, room temperature synthesis of UO 2+ x nanoparticles and thin films using solution processable, molecular uranium( iv ) compounds is described. Ultra-small uranium dioxide nanoparticles are synthesized from the hydrolysis of either U(ditox) 4 (ditox = − OCH t Bu 2 ) (1) or U(CH 2 SiMe 2 NSiMe 3 )[N(SiMe 3 ) 2 ] 2 (2) via addition of water to stirring solutions of the compounds in non-polar solvents to give UO 2 -1 and UO 2 -2, respectively. The structural characteristics of the uranium dioxide nanoparticles were characterized using powder X-ray diffraction (pXRD), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. The pXRD results affirm the cubic fluorite structure expected for UO 2 nanoparticles. The nanocrystallinity of UO 2 -1 and UO 2 -2 were substantiated by bright-field HRTEM images and fast Fourier transform (FFT) patterns. The HRTEM analysis also shows the nanoparticles fall within the ultra-small regime possessing sizes of ∼3 nm with uniform distribution. Additionally, we demonstrate the versatility of 1 as a uranium dioxide precursor, showing that it can be readily sublimed onto glass or silicon substrates and subsequently hydrolyzed to give UO 2+ x thin films. 
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  3. The syntheses of [2-(CH 3 ECH 2 )C 6 H 4 ]PbPh 3− n Cl n , ( n = 0, E = O (4), E = S (5); n = 1, E = O (6), E = S (7); n = 2, E = O (8), are described. NMR and single crystal data illustrate significant Pb⋯E interactions increasing as n progresses from 0 to 2. The Pb⋯E interactions stabilize the Pb–aryl bonding to the extent that the reactions of 4 and 5 with Me 2 SnCl 2 result in interchange of a Ph group and Cl to produce 6 and 7, respectively, together with Me 2 PhSnCl. 
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  4. Addition of [UI 2 (THF) 3 (μ-OMe)] 2 ·THF (2·THF) to THF solutions containing 6 equiv. of K[C 14 H 10 ] generates the heteroleptic dimeric complexes [K(18-crown-6)(THF) 2 ] 2 [U(η 6 -C 14 H 10 )(η 4 -C 14 H 10 )(μ-OMe)] 2 ·4THF (118C6·4THF) and {[K(THF) 3 ][U(η 6 -C 14 H 10 )(η 4 -C 14 H 10 )(μ-OMe)]} 2 (1THF) upon crystallization of the products in THF in the presence or absence of 18-crown-6, respectively. Both 118C6·4THF and 1THF are thermally stable in the solid-state at room temperature; however, after crystallization, they become insoluble in THF or DME solutions and instead gradually decompose upon standing. X-ray diffraction analysis reveals 118C6·4THF and 1THF to be structurally similar, possessing uranium centres sandwiched between bent anthracenide ligands of mixed tetrahapto and hexahapto ligation modes. Yet, the two complexes are distinguished by the close contact potassium-arenide ion pairing that is seen in 1THF but absent in 118C6·4THF, which is observed to have a significant effect on the electronic characteristics of the two complexes. Structural analysis, SQUID magnetometry data, XANES spectral characterization, and computational analyses are generally consistent with U( iv ) formal assignments for the metal centres in both 118C6·4THF and 1THF, though noticeable differences are detected between the two species. For instance, the effective magnetic moment of 1THF (3.74 μ B ) is significantly lower than that of 118C6·4THF (4.40 μ B ) at 300 K. Furthermore, the XANES data shows the U L III -edge absorption energy for 1THF to be 0.9 eV higher than that of 118C6·4THF, suggestive of more oxidized metal centres in the former. Of note, CASSCF calculations on the model complex {[U(η 6 -C 14 H 10 )(η 4 -C 14 H 10 )(μ-OMe)] 2 } 2− (1*) shows highly polarized uranium–arenide interactions defined by π-type bonds where the metal contributions are primarily comprised by the 6d-orbitals (7.3 ± 0.6%) with minor participation from the 5f-orbitals (1.5 ± 0.5%). These unique complexes provide new insights into actinide–arenide bonding interactions and show the sensitivity of the electronic structures of the uranium atoms to coordination sphere effects. 
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  5. null (Ed.)
    Abstract The tetrahedral geometry of organolead(IV) compounds can be readily transformed by using an organic ligand containing a dangling-arm oxygen functionality. The acidity of the Pb center results in so-called secondary bonding between O and Pb thereby pushing the geometry at Pb toward a trigonal bipyramidal (tbp) structure. Replacing a phenyl group by a chlorine atom dramatically enhances this phenomenon. Thus for (o-methoxybenzyl) triphenyllead (4), and (o-methoxybenzyl)diphenyllead chloride (5), the Pb–O internuclear distances are 3.362(4) and 2.845(3) Å, respectively; 83% (4) and 70% (5) of the sum of the van der Waals Pb and O radii. Within the group 14 element congeners the structural analysis of the (o-methoxybenzyl)triphenylE compounds, E = Si, Ge, Sn, and now Pb, demonstrates the relative acidities of E are Si < Ge < Sn < Pb. 
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  6. null (Ed.)
    Dy-based single-molecule magnets (SMMs) are of great interest due to their ability to exhibit very large thermal barriers to relaxation and therefore high blocking temperatures. One interesting line of investigation is Dy-encapsulating endohedral clusterfullerenes, in which a carbon cage protects magnetic Dy 3+ ions against decoherence by environmental noise and allows for the stabilization of bonding and magnetic interactions that would be difficult to achieve in other molecular architectures. Recent studies of such materials have focused on clusters with two Dy atoms, since ferromagnetic exchange between Dy atoms is known to reduce the rate of magnetic relaxation via quantum tunneling. Here, two new dysprosium-containing mixed-metallic sulfide clusterfullerenes, DyScS@ C s (6)–C 82 and DyScS@ C 3v (8)–C 82 , have been successfully synthesized, isolated and characterized by mass spectrometry, Vis-NIR, cyclic voltammetry, single crystal X-ray diffractometry, and magnetic measurements. Crystallographic analyses show that the conformation of the encapsulated cluster inside the fullerene cages is notably different than in the Dy 2 X@ C s (6)–C 82 and Dy 2 X@ C 3v (8)–C 82 (X = S, O) analogues. Remarkably, both isomers of DyScS@C 82 show open magnetic hysteresis and slow magnetic relaxation, even at zero field. Their magnetic blocking temperatures are around 7.3 K, which are among the highest values reported for clusterfullerene SMMs. The SMM properties of DyScS@C 82 far outperform those of the dilanthanide analogues Dy 2 S@C 82 , in contrast to the trend observed for carbide and nitride Dy clusterfullerenes. 
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  7. null (Ed.)