A Planar,Conjugated N4‐Macrocyclic Cobalt Complex for Heterogeneous Electrocatalytic CO2 Reduction with High Activity

Metal complexes have been widely investigated as promising electrocatalysts for CO₂ reduction. Most of the current research efforts focus mainly on ligands based on pyrrole subunits, and the reported activities are still far from satisfactory. A novel planar and conjugated N₄‐macrocyclic cobalt complex (Co(II)CPY) derived from phenanthroline subunits is prepared herein, and it delivers high activity for heterogeneous CO₂ electrocatalysis to CO in aqueous media, and outperforms most of the metal complexes reported so far. At a molar loading of 5.93×10^?8 mol cm^?2, it exhibits a Faradaic efficiency of 96 % and a turnover frequency of 9.59 s^?1 towards CO at ?0.70 V vs. RHE. The unraveling of electronic structural features suggests that a synergistic effect between the ligand and cobalt in Co(II)CPY plays a critical role in boosting its activity. As a result, the free energy difference for the formation of *COOH is lower than that with cobalt porphyrin, thus leading to enhanced CO production.     

Cu Nanoparticles Embedded in N‐Doped Carbon Materials for Oxygen Reduction Reaction

Development of eco‐friendly, cost‐effective, and high‐performance electrocatalysts to replace precious metal platinum for oxygen reduction reaction (ORR) has received increasing attention. Herein, we adopt a facile one‐pot strategy to embed Cu nanoparticles onto N‐doped carbon‐graphene (Cu@NC‐700). The Cu@NC‐700 exhibits robust and efficient ORR catalysis with positive half‐wave potential (~0.86 V vs. RHE) and low Tafel slope (33.9 mV?dec^–1) in 0.1 M KOH solution. Meanwhile, it manifests remarkable electrochemical stability, and strong tolerance to methanol crossover and carbon monoxide poisoning. The synergistic effect between Cu‐N‐C sites, Cu nanoparticles, and N‐doped carbon support speeds up ORR electrocatalysis.     

SBA‐15‐Oxynitrides as a Solid‐Base Catalyst: Effect of Nitridation Temperature on Catalytic Activity

Solid bases, such as SBA‐15‐oxynitrides, have attracted considerable interest for potential applications as catalysts in important industrial processes. Reported herein is that by simply tuning the temperature of nitridation (ammonolysis), the catalytic activity of these solid bases can be enhanced. Solid‐state NMR spectroscopy and XPS studies provided the reasoning behind this change in activity.     

“Metal‐Free” Catalytic Oxygen Reduction Reaction on Heteroatom‐Doped Graphene is Caused by Trace Metal Impurities

The oxygen reduction reaction (ORR) is of high industrial importance. There is a large body of literature showing that metal‐based catalytic nanoparticles (e.g. Co, Mn, Fe or hybrid Mn/Co‐based nanoparticles) supported on graphene act as efficient catalysts for the ORR. A significant research effort is also directed to the so‐called “metal‐free” oxygen reduction reaction on heteroatom‐doped graphene surfaces. While such studies of the ORR on nonmetallic heteroatom‐doped graphene are advertised as “metal‐free” there is typically no sufficient effort to characterize the doped materials to verify that they are indeed free of any trace metal. Here we argue that the claimed “metal‐free” electrocatalysis of the oxygen reduction reaction on heteroatom‐doped graphene is caused by metallic impurities present within the graphene materials.     

1‐Amino‐2‐fluoromonocarba‐closo‐dodecaborates: K[1‐H2N‐2‐F‐closo‐1‐CB11H10] and [Et4N][1‐H2N‐2‐F‐closo‐1‐CB11I10]

The potassium salt of the [1‐H₂N‐2‐F‐closo‐1‐CB₁₁H₁₀]^– anion ( 1 ) was obtained from an insertion reaction of Li₃[7‐H₂N‐nido‐7‐CB₁₀H₁₀] with BF₃ · OEt₂. Anion 1 was protonated to the neutral species 1‐H₃N‐2‐F‐closo‐1‐CB₁₁H₁₀ (H 1 ) and it was iodinated with ICl to the [1‐H₂N‐2‐F‐closo‐1‐CB₁₁I₁₀]^– anion ( 2 ). All species were characterized by multinuclear NMR, IR, and Raman spectroscopy as well as by elemental analysis. The structure of H 1· (CH₃)₂CO was studied by single‐crystal X‐ray diffraction and the experimentally determined bond lengths are compared to values derived from density functional calculations.     

LiLa5Si4N10O and LiPr5Si4N10O – Chain‐Type Oxonitridosilicates

The isotypic lithium rare‐earth oxonitridosilicates LiLn₅Si₄N₁₀O (Ln = La, Pr) were synthesized at temperatures of 1200 °C in weld shut tantalum ampoules employing liquid lithium as flux. Thereby, a silicate substructure with a low degree of condensation was obtained. LiLa₅Si₄N₁₀O crystallizes in space group P$\bar{1}$ [Z = 1, LiLa₅Si₄N₁₀O: a = 5.7462(11), b = 6.5620(13), c = 8.3732(17) Å, α = 103.54(3), β = 107.77(3), γ = 94.30(3), wR₂ = 0.0405, 1315 data, 96 parameters]. The nitridosilicate substructure consists of loop branched dreier single‐chains of vertex sharing SiN₄ tetrahedra. Lattice energy calculations (MAPLE) and EDX measurements confirmed the electrostatic bonding interactions and the chemical compositions. The ⁷Li solid‐state MAS NMR investigation is reported.     

Zn8[P12N24]O2 – ein Nitridophosphat‐oxid mit Sodalith‐Struktur

Zn₈P₁₂N₂₄O₂ – a Nitridophosphate Oxide with Sodalite Structure The reaction between zinc metal and phosphorus nitride imide PN(NH) was investigated. Surprisingly, no Zn₆P₁₂N₂₄ was formed as assumed in former investigations but phase pure Zn₈[P₁₂N₂₄]O₂ ( (Nr. 217), a = 8.2422(2) Å; Z = 1) was obtained due to contamination by a small amount of oxygen. The existence of Zn₈[P₁₂N₂₄]O₂ was formerly supposed, but neither its crystal structure nor its exact composition have been unequivocally reported so far. The stoichiometric formula was deducted from elemental analyses, XANES spectroscopy at the phosphorus K‐threshold and IR‐spectroscopy using the crystallographic results of electron diffraction, X‐ray powder diffraction and solid‐state NMR spectroscopy. Zn₈[P₁₂N₂₄]O₂ adopts the sodalite structure type and is thus isotypic with Zn₈[P₁₂N₂₄]X₂ with X = S, Se, Te and Zn₈[B₁₂O₂₄]O₂.     

Synthesis and Solid‐state Reaction of 1‐[3′‐(Benzotriazol‐2″‐yl)‐4′ ‐hydroxybenzoyl]‐3‐methyl‐5‐pyrazolones

A new kind of UV stabilizers, 1‐(3′‐(benzotriazol‐2″‐yl)‐4′‐hydroxy‐benzoyl)‐3‐methyl‐5‐pyrazolones (1a‐d), was synthesized with the aim to bind them chemically to certain polymers. The reaction of 1d with substituted benzaldehydes 4 in the molten state at 150°C and in the solid state at room temperature produced the condensation products l‐(3′‐(5″‐chlorobenzotriazol‐2″‐yl)‐4′‐hydroxyl‐5′‐chlorobenzoyl)‐3‐methyl‐4‐arylmethylene‐5‐pyrazolones (2) and 4,4′‐arylmethylene‐bis [1‐(3′‐(5″‐chloro‐benzotriazol‐2″‐yl)‐4′‐hydroxy‐5′‐chloro‐benzoyl)‐3‐methyl‐5‐pyrazolone] s (3), respectively, as the major product. On the other hand, the reaction of 1d with 4 at 50°C in chloroform solution proceeded non‐selectively to give a mixture of 2 and 3.     

Main‐Chain Organometallic Microporous Polymers Bearing Triphenylene–Tris(N‐Heterocyclic Carbene)–Gold Species: Catalytic Properties

Two triphenylene‐based tris(N‐heterocyclic carbene)–gold–acetylide main‐chain organometallic microporous polymers (MOMPs) were obtained and fully characterized. Both materials show spherical shapes, and their size is highly dependent on the type of acetylene used in the synthetic protocol. The new solids were tested in the catalytic reduction of nitroarenes with NaBH₄ and in the three‐component Strecker reaction for the synthesis of α‐aminonitriles, and showed high activity in both processes. Whereas the activity of the solids in the reduction of nitroarenes may be attributed to the formation of Au nanoparticles due to the use of NaBH₄ as reducing agent, the activity in the Strecker reaction may originate from the Lewis acidic activation of the ketone or imine on coordination to Au.     

Understanding the Activity of Co‐N4−xCx in Atomic Metal Catalysts for Oxygen Reduction Catalysis

Atomic metal catalysis (AMC) provides an effective way to enhance activity for the oxygen reduction reaction (ORR). Cobalt anchored on nitrogen‐doped carbon materials have been extensively reported. The carbon‐hosted Co‐N₄ structure was widely considered as the active site; however, it is very rare to investigate the activity of Co partially coordinated with N, for example, Co‐N_4?xC_x. Herein, the activity of Co‐N_4?xC_x with tunable coordination environment is investigated as the active sites for ORR catalysis. The defect (di‐vacancies) on carbon is essential for the formation of Co‐N_4?xC_x. N species play two important roles in promoting the intrinsic activity of atomic metal catalyst: N coordinated with Co to manipulate the reactivity by modification of electronic distribution and N helped to trap more Co to increase the number of active sites.     

Synergistic Enhancement of Electrocatalytic Activity toward Oxygen Reduction Reaction in Alkaline Electrolytes with Pentabasic (Fe,B, N,S, P)‐Doped Reduced Graphene Oxide

As alternatives to Pt‐based electrocatalysts, the development of nonprecious metal catalysts with high performance in the cathodic oxygen reduction reaction (ORR) is highly desirable for widespread use in fuel cells. Here we report a simple approach for preparing pentabasic (Fe, B, N, S, P)‐doped reduced graphene oxide (rGO) via a two‐step doping method of adding boric acid and ferric chloride to ternary (N, S, P)‐doped rGO (NSPG). Electrochemical investigation of the composites for the ORR revealed that simultaneously doping appropriate amounts of Fe and B into the NSPG produced a synergistic effect that endowed the prepared catalyst with both a positively shifted ORR half‐wave potential and high selectivity for the 4e^? reduction of O₂. The optimized Fe₂B‐NSPG catalyst approached a 4e^? process for the ORR with a half‐wave potential (E_1/2=0.90 V vs. RHE) even 30 mV higher than that of the commercial Pt/C catalyst in alkaline solution. Furthermore, relative to the Pt/C catalyst, the Fe₂B‐NSPG demonstrated superior stability and excellent tolerance of the methanol cross‐over effect. This simple method afforded pentabasic (Fe, B, N, S, P)‐doped rGO as a promising nonprecious metal catalyst used for alkaline fuel cells.     

Supported Organometallic Complexes. XXXVI [1] Diaminediphosphineruthenium(II) Interphase Catalysts for the Hydrogenation of α, β‐Unsaturated Ketones

The T—silyl functionalized diamine‐bis(ether‐phosphine)ruthenium(II) complexes 1a(T ° ) — 1g(T ° ) (Scheme 1) were sol‐gel processed in the presence of different amounts of the co‐condensation agents CH₃Si(OMe)₃ (Me—T ° ) and (MeO)₂SiMe—(CH₂)₆—MeSi(OMe)₂ (D ° —C₆—D ° ) to produce a library of the interphase catalysts X1a — X1c , X2a — X2g , and X3a — X3g . Due to the remarkable electronic and steric effects of the co‐ligands on the catalytic activity of such complexes, a series of aliphatic and aromatic diamines was selected. The new polymers were investigated by multinuclear CP/MAS solid‐state NMR spectroscopy as well as by EXAFS, EDX, SEM, and BET methods. Selected interphase catalysts show high activities and selectivities in the hydrogenation of trans‐4‐phenyl‐3‐butene‐2‐one.     

Bis(N‐acetyltriethylphosphaniminium)‐tetraacetato‐dichloro‐dicuprat(II), [MeC(O)N(H)PEt3]2[Cu2(O2C–Me)4Cl2]

Bis(N‐acetyltriethylphosphaneiminium)‐tetraacetato‐dichloro‐dicuprate(II), [MeC(O)N(H)PEt₃]₂[Cu₂(O₂C–Me)₄Cl₂] The title compound has been prepared by the reaction of Me₃SiNPEt₃ with [Cu₂(O₂C–Me)₄] and MeC(O)Cl in dichloromethane solution to give colourless crystals which include four molecules CH₂Cl₂ per formula unit. The complex is characterized by IR spectroscopy and by a crystal structure determination. [MeC(O)N(H)PEt₃]₂[Cu₂(O₂C–Me)₄Cl₂] · 4 CH₂Cl₂: Space group P2₁/n, Z = 2, lattice dimensions at –70 °C: a = 794.1(1), b = 2356.9(6), c = 1327.3(2) pm; β = 91.00(1)°; R₁ = 0.0597. The structure consists of N‐acetyltriethylphosphaneiminium cations and dianions [Cu₂(O₂C–Me)₄Cl₂]^2– which form an iontriple with N–H…Cl hydrogen bridges.     

Crystallographic report: Chloro[1,3‐bis[2‐[2‐[(4‐methoxybenzyl) amino]ethylamino]]‐2‐propanol]zinc(II) chloride hydrate, [(C23H36N4O3)ZnCl]Cl·H2O

The zinc(II) center in the molecule of [(C₂₃H₃₆N₄O₃)ZnCl]Cl·H₂O is coordinated by four nitrogen atoms of HL (1,3‐bis[2‐[2‐[(4‐methoxybenzyl) amino]ethylamino]]‐2‐propanol) and one chloro anion. The coordination moieties are connected by hydrogen bonds to form a one‐dimensional structure. Copyright © 2005 John Wiley & Sons, Ltd.     

Two‐Orbital Three‐Electron Stabilizing Interaction for Direct Co2+As3+ Bonds involving Square‐Planar CoO4 in BaCoAs2O5

The quest for new oxides with cations containing active lone‐pair electrons (E) covers a broad field of targeted specificities owing to asymmetric electronic distribution and their particular band structure. Herein, we show that the novel compound BaCoAs₂O₅, with lone‐pair As³⁺ ions, is built from rare square‐planar Co²⁺O₄ involved in direct bonding between As³⁺E and Co²⁺ d_z2 orbitals (Co? As=2.51 Å). By means of DFT and Hückel calculations, we show that this σ‐type overlapping is stabilized by a two‐orbital three‐electron interaction allowed by the high‐spin character of the Co²⁺ ions. The negligible experimental spin‐orbit coupling is expected from the resulting molecular orbital scheme in O₃AsE–CoO₄ clusters.