Ineffective OH Pinning of the Flipping Dynamics of a Spherical Guest within a Tight‐Fitting Tube

A supramolecular/synthetic method has been devised to affix a sterically hindered substituent onto a fullerene guest encapsulated in a tubular host. A two‐wheeled complex of (C₅₉N)‐(C₅₉N) with a tubular host was oxidatively bisected to afford a C₅₉N⁺ cation captured in the tube. The C₅₉N⁺ cation in the tube was then trapped by ethanol or water, which led to an oxy substituent pinned on the guest. The guest motions within the tube were modulated by the pinned substituent, and up‐and‐down flipping motions were halted by an ethoxy substituent. A hydroxy substituent, however, was ineffective in halting the flipping motions, despite the tight‐fitting relationship between the tubular host and the spherical guest. Theoretical calculations of the dynamics revealed that the flipping motions were assisted by OH‐π hydrogen bonds between the guest and the carbon‐rich wall and that sliding motions of the OH group were also facilitated by deformations of the tube.     

On‐Surface Synthesis of NBN‐Doped Zigzag‐Edged Graphene Nanoribbons

We report the first bottom‐up synthesis of NBN‐doped zigzag‐edged GNRs (NBN‐ZGNR1 and NBN‐ZGNR2) through surface‐assisted polymerization and cyclodehydrogenation based on two U‐shaped molecular precursors with an NBN unit preinstalled at the zigzag edge. The resultant zigzag‐edge topologies of GNRs are elucidated by high‐resolution scanning tunneling microscopy (STM) in combination with noncontact atomic force microscopy (nc‐AFM). Scanning tunneling spectroscopy (STS) measurements and density functional theory (DFT) calculations reveal that the electronic structures of NBN‐ZGNR1 and NBN‐ZGNR2 are significantly different from those of their corresponding pristine fully‐carbon‐based ZGNRs. Additionally, DFT calculations predict that the electronic structures of NBN‐ZGNRs can be further tailored to be gapless and metallic through one‐electron oxidation of each NBN unit into the corresponding radical cations. This work reported herein provides a feasible strategy for the synthesis of GNRs with stable zigzag edges yet tunable electronic properties.     

An N‐Heterocyclic‐Carbene‐Derived Distonic Radical Cation

We present the discovery of a novel radical cation formed through one‐electron oxidation of an N‐heterocyclic carbene–carbodiimide (NHC–CDI) zwitterionic adduct. This compound possesses a distonic electronic structure (spatially separate spin and charge regions) and displays persistence under ambient conditions. We demonstrate its application in a redox‐flow battery exhibiting minimal voltage hysteresis, a flat voltage plateau, high Coulombic efficiency, and no performance decay for at least 100 cycles. The chemical tunability of NHCs and CDIs suggests that this approach could provide a general entry to redox‐active NHC–CDI adducts and their persistent radical ions for various applications.     

Synthesis of Low-Valent Dinuclear Group 14 Compounds with Element–Element Bonds by Transylidation

Dinuclear low-valent compounds of the heavy main group elements are rare species owing to their intrinsic reactivity. However, they represent desirable target molecules due to their unusual bonding situations as well as applications in bond activations and materials synthesis. The isolation of such compounds usually requires the use of substituents that provide sufficient stability and synthetic access. Herein, we report on the use of strongly donating ylide-substituents to access low-valent dinuclear group 14 compounds. The ylides not only impart steric and electronic stabilization, but also allow facile synthesis via transfer of an ylide from tetrylene precursors of type ^RY₂E to ECl₂ (E=Ge, Sn; ^RY=TolSO₂(PR₃)C with R=Ph, Cy). This method allowed the isolation of dinuclear complexes amongst a germanium analogue of a vinyl cation, [(^PhY)₂GeGe(^PhY)]⁺ with an electronic structure best described as a germylene-stabilized Ge^II cation and a ylide(chloro)digermene [^CyY(Cl)GeGe(Cl)^CyY] with an unusually unsymmetrical structure.     

Carbeniophosphines versus Phosphoniocarbenes: The Role of the Positive Charge

The chemistry of carbeniophosphines and phosphoniocarbenes, which have general structures derived formally from the three‐component “carbene/phosphine/positive charge” association, is presented. These two complementary classes of carbon–phosphorus‐based ligands, defined by the presence of an inverted cationic coordinating structure (C⁺～P: vs. P⁺～C:) have the common purpose of positioning a positive charge in the vicinity of the metal center. Through selected examples, the synthetic methods, coordination properties, and general reactivity of both cationic species is described. Particular emphasis is placed on the influence of the positive charge on the respective chemical behavior of the two classes of compound.     

A highly diastereoselective [3+3] annulation reaction of aza-oxyallyl cations and nitrones

An efficient synthesis of 1,2,4-oxadiazinan-5-ones via [3+3] cycloaddition of in situ generated aza-oxyallyl cations with nitrones has been developed. The protocol features easy operation, excellent yields, excellent diastereo-control, broad substrate scope and good functional group tolerance.     

Vibrational Spectra of Arsenates and Phosphates of the Type Kcaln(XO4)2

The infrared and Raman spectra of polycrystal-line samples of different compounds of the types KCaLn(AsO₄)₂ and KCaLn(PO₄)₂, belonging to the hexagonal LaPO₄, structural modification, were recorded and discussed. A complete vibrational assignment, based on a factor group analysis, is proposed. The influence of the different lanthanide cations on the internal vibrations of the XO₄ groups is briefly discussed and some comparisons with related compounds are also made.

It is well known that simple lanthanide arsenates, phosphates, vanadates and cnromates (V) of the type LnXO₄ belong to two different structural types.     

Effect of Cation Nonstoichiometry on the Properties of Solid Electrolyte Ba x Ce0.97Nd0.03O3 - δ (0.90 ≤ x ≤ 1.10)

The effect of the cation nonstoichiometry on the electroconduction, electrotransfer, and stability in humid air of solid proton-conducting electrolyte Ba _x Ce_0.97Nd_0.03O_{3 -} (0.90 x 1.10) is studied. The electroconduction is found to decrease with decreasing content of BaO (x 1.0) and weakly depend on the BaO excess (x> 1.0). Ceramics of a stoichiometric composition (x = 1) and with lack of barium is stable when stored in humid air at room temperature, as opposed to the ceramics with barium excess, which rapidly decomposes in these conditions. The conduction of materials under study in oxidizing environment is ion-hole and in reducing media, ionic (proton + oxygen). The cation nonstoichiometry barely affects the nature of the ion transfer. An analysis of possible models for the formation of defects shows oxygen vacancies to be always present in Ba _x Ce_0.97Nd_0.03O_{3 -} , even at the CeO₂ excess exceeding the content of neodymium.