Counterion Dependence of Dinitrogen Activation and Functionalization by a Diniobium Hydride Anion

We report the synthesis of anionic diniobium hydride complexes with a series of alkali metal cations (Li⁺, Na⁺, and K⁺) and the counterion dependence of their reactivity with N₂. Exposure of these complexes to N₂ initially produces the corresponding side‐on end‐on N₂ complexes, the fate of which depends on the nature of countercations. The lithium derivative undergoes stepwise migratory insertion of the hydride ligands onto the aryloxide units, yielding the end‐on bridging N₂ complex. For the potassium derivative, the N?N bond cleavage takes place along with H₂ elimination to form the nitride complex. Treatment of the side‐on end‐on N₂ complex with Me₃SiCl results in silylation of the terminal N atom and subsequent N?N bond cleavage along with H₂ elimination, giving the nitride‐imide‐bridged diniobium complex.     

Halogen-Substituted Cyclotrigermenes: The π(Ge = Ge)-σ*(Ge–X) Interaction and a Unique Dynamic Behavior

Abstract

The halogen-substituted cyclotrigermenes (^tBu₃Si)₃Ge₃X (X = F, Cl, Br, I) (2) were synthesized by the reaction of tris(tri-tert-butylsilyl)cyclotrigermenylium tetrakis(2,3,5,6-tetrafluorophenyl)borate) (1 ⁺?TTFPB^?) with potassium halides (KF, KCl, KBr, KI). Intramolecular halogen migration over the three-membered ring skeleton was observed in the solution.

GRAPHICAL ABSTRACT     

Improved dehydrogenation/rehydrogenation performance of LiBH4 by doping mesoporous Fe2O3 or/and TiF3

The LiBH₄ + mesoporous Fe₂O₃ (defined as M-Fe₂O₃) mono-doped and LiBH₄ + M-Fe₂O₃ + TiF₃ co-doped hybrid materials were prepared by ball milling process. A variety of characterization methods, such as thermogravimetric, differential scanning calorimetry, X-ray diffraction, and pressure–composition–temperature instrument, were used for examinations of the two materials’ performances of storage/release of hydrogen, catalytic activity, kinetics, and thermodynamics. All the results showed that the M-Fe₂O₃ prepared in laboratory exhibited a good catalytic effect. Compared with the performance of M-Fe₂O₃ mono-doped system, M-Fe₂O₃ and TiF₃ co-doped mode exhibits a better performance using the same additive content. Thus, the M-Fe₂O₃ and TiF₃ co-doped mode possesses a collaborative catalytic utility with the LiBH₄ hydrogen performance improved, showing a promising application.     

Bulk heterojunction organic photovoltaic cell fabricated by the electrospray deposition method using mixed organic solvent

A high‐efficiency bulk heterojunction organic photovoltaic cell (OPV) was achieved by the electrospray deposition method. The surface roughness of the P3HT:PCBM thin film can be reduced using the mixed solvent consisting of o‐dichlorobenzene (o‐DCB) and acetone. The effect of acetone concentration is related to its dielectric constant. Under an optimized concentration of acetone in o‐DCB (20 vol%), the P3HT/PCBM active layer with a smooth surface can be formed, and the power conversion efficiency of the OPV was 1.9%.

     

First examples of hypervalent enhancement of photoallylation by allylsilicon compounds via photoinduced electron transfer

Hypervalency (pentacoordination) of silicon atom enhanced photoallylation of 1,2-diketones with allylsilicon reagents, while normal tetracoordinated ones could not. This reaction seems to proceed via photoinduced electron transfer from the silicon reagent to the photoexcited ketone judged from its reactivity and selectivity.     

Lewis Acid-Induced Dinitrogen Cleavage in an Anionic Side-on End-on Bound Dinitrogen Diniobium Hydride Complex

The side-on end-on dinitrogen hydride complex [{Na(dme)}₂{(O₃)Nb}₂(μ-η¹:η²-N₂)(μ-H)₂] (3-Na, [O₃]³⁻ = [(3,5-^tBu₂-2-O-C₆H₂)₃CH]³⁻) was observed to undergo facile elimination of H₂ and cleavage of the N–N bond in the presence of 9-borabicyclo[3.3.1]nonane (9-BBN), AlMe₃, and ZnMe₂. Treatment of 3-Na with 9-BBN and ZnMe₂ afforded the nitride complex [{K(dme)₂}₂{(O₃)Nb}₂(μ-N)₂] (2-Na). The reaction of 3-Na with AlMe₃ afforded [{Na(dme)}₂{(O₃)AlMe}₂(NbMe₂)₂(μ-N)₂] (5). The nitride complex 2-Na was treated with 9-BBN and AlMe₃ to form [{Na(dme)}₂{(O₃)Nb}(μ-NH)(μ-NBC₈H₁₄){Nb(O₃C)}] (4) and 5, respectively. Complex 2-Na, 4, and 5 were structurally characterized.     

Nano-Graphites and their Potassium Intercalated Compounds: Structural and Electronic Properties

Abstract

Graphite-nano particles were prepared by the heat-treatment of diamond-nano particles. Various heat-treatment temperatures in the range 900–1600°C were used. X-ray diffraction studies indicate that the onset temperature of diamond-graphite transition is around 1000°C and the complete conversion of diamond to graphite occurs at 1600°C. X-ray diffraction studies on the potassium intercalated compounds of these graphite-nano particles, while indicating the absence of staging phenomenon, show that small neutral potassium clusters are included in these intercalated compounds. The presence of neutral potassium clusters could also explain the observed magnetic susceptibilities and the large deviations in the ESR g-values of these intercalated nano-graphitic systems.