Stability Of NH Research Articles

Stabilization of NH- Group Adjacent to Naked Silicon(II) Atom in Base Stabilized Aminosilylenes.

Aminosilylene, comprising reactive NH- and Si(II) sites next to each other, is an intriguing class of compounds due to its ability to show diverse reactivity. However, stabilizing the reactive NH- group next to the free Si(II) atom is challenging and has not yet been achieved. Herein, we report the first examples of base stabilized free aminosilylenes Ar*NHSi(PhC(Nt Bu)2 ) (1 a) and Mes*NHSi(PhC(Nt Bu)2 ) (1 b) (Ar*=2,6-dibenzhydryl-4-methylphenyl and Mes*=2,4,6-tri-tert-butylphenyl), tolerating a NH- group next to the naked Si(II) atom. Remarkably, 1 a and 1 b exhibited interesting differences in their reactivity upon heating. With 1 a, an intramolecular C(sp3 )-H activation of one of the benzhydryl methine hydrogen atoms to the Si(II) atom produced the five-membered cyclic silazane 2. However, with 1 b, a rare 1,2-hydrogen shift to the Si(II) atom afforded a silanimine 3, with a hydride ligand attached to an unsaturated silicon atom. Further, the coordination capabilities of 1 a were also tested with Ru(II) and Fe(0) precursors. Treatments of 1 a with [Ru(η6 -p-cymene)Cl2 ]2 led to the isolation of a η6 -arene tethered complex [RuCl2 {Ar*NHSi(PhC(t BuN)2 )-κ1 -Si-η6 -arene}] (4), whereas with the Fe(CO)5 precursor a Fe(0) complex [Fe(CO)4 {Ar*NHSi(PhC(t BuN)2 )-κ1 -Si}] (5) was obtained. Density functional theory (DFT) calculations were conducted to shed light on the structural, bonding, and energetic aspects in 1-5.

Stabilization of NH− Group Adjacent to Naked Silicon(II) Atom in Base Stabilized Aminosilylenes

AbstractAminosilylene, comprising reactive NH− and Si(II) sites next to each other, is an intriguing class of compounds due to its ability to show diverse reactivity. However, stabilizing the reactive NH− group next to the free Si(II) atom is challenging and has not yet been achieved. Herein, we report the first examples of base stabilized free aminosilylenes Ar*NHSi(PhC(NtBu)2) (1 a) and Mes*NHSi(PhC(NtBu)2) (1 b) (Ar*=2,6‐dibenzhydryl‐4‐methylphenyl and Mes*=2,4,6‐tri‐tert‐butylphenyl), tolerating a NH− group next to the naked Si(II) atom. Remarkably, 1 a and 1 b exhibited interesting differences in their reactivity upon heating. With 1 a, an intramolecular C(sp3)−H activation of one of the benzhydryl methine hydrogen atoms to the Si(II) atom produced the five‐membered cyclic silazane 2. However, with 1 b, a rare 1,2‐hydrogen shift to the Si(II) atom afforded a silanimine 3, with a hydride ligand attached to an unsaturated silicon atom. Further, the coordination capabilities of 1 a were also tested with Ru(II) and Fe(0) precursors. Treatments of 1 a with [Ru(η6‐p‐cymene)Cl2]2 led to the isolation of a η6‐arene tethered complex [RuCl2{Ar*NHSi(PhC(tBuN)2)‐κ1‐Si‐η6‐arene}] (4), whereas with the Fe(CO)5 precursor a Fe(0) complex [Fe(CO)4{Ar*NHSi(PhC(tBuN)2)‐κ1‐Si}] (5) was obtained. Density functional theory (DFT) calculations were conducted to shed light on the structural, bonding, and energetic aspects in 1–5.

Dual effects of Ag+ intercalation boosting the kinetics and stability of NH4V4O10 cathodes for enhanced zinc ion storage

The present work simultaneously addresses the structural instability and poor diffusion kinetics of NH4V4O10 cathodes using Ag+ intercalation, providing a new perspective on transition metal ion intercalation towards high-performance cathodes for AZIBs.

Preparation and gas sensing properties of a novel two-dimensional material Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x </i></sub>MXene

Since the discovery of graphene materials, two-dimensional materials have been widely recognized and gradually applied. Two-dimensional transition metal carbides (MXenes) have better mechanical, magnetic and electrical properties than traditional two-dimensional materials. In this work, Ti<sub>3</sub>C<sub>2</sub>T<i><sub>x</sub></i> samples are prepared by etching Ti<sub>3</sub>AlC<sub>2</sub> with different etching agents for the solutions of HF and LiF/HCl. The effects of etching agents on the structure and gas sensing properties of Ti<sub>3</sub>C<sub>2</sub>T<i><sub>x</sub></i> materials are studied by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and gas sensing properties analysis. The material structure analysis shows that both HF and LiF/HCl etching agents have good etching effect on Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> material. The results of gas sensing properties show that the gas sensing properties of Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> prepared by LiF/HCl etching agent is better than by HF etching agent, and the wide range, high sensitivity and high stability of NH<sub>3</sub> detection can be achieved at room temperature. The analysis shows that the high sensing performance of Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> prepared by LiF/HCl solution etching is mainly due to the high proportion of —O and —OH functional groups on the surface of Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>. The experimental studies can lay a theoretical foundation for studying the gas sensing and practical application of Ti<sub>3</sub>C<sub>2</sub>T<i><sub>x</sub></i> based sensor.

Crystallographic Investigations into Properties of Acentric Hybrid Perovskite Single Crystals NH(CH3)3SnX3 (X = Cl, Br)

The hybrid perovskites with special optoelectronic properties have attracted more attention to the scientific and industrial applications. However, because of the toxicity and instability of lead complexes, there is interest in finding a nontoxic substitute for the lead in the halides perovskites and solving the ambiguous crystal structures and phase transition of NH(CH3)3SnX3 (X = Cl, Br). Here, we report the bulk crystal growths and different crystal morphologies of orthorhombic hybrid perovskites NH(CH3)3SnX3 (X = Cl, Br) in an ambient atmosphere by bottom-seeded solution growth (BSSG) method. More importantly, detailed structural determination and refinements, phase transition, band gap, band structure calculations, nonlinear optical (NLO) properties, XPS, thermal properties, and stability of NH(CH3)3SnX3 (X = Cl, Br) single crystals are demonstrated. NH(CH3)3SnCl3 single crystal undergoes reversible structural transformation from orthorhombic space group Cmc21 (no. 36) to monoclinic space group Cc (n...

Subcellular NH4 + flux analysis in leaf segments of wheat (Triticum aestivum).

• We report the first use of tracer 13 NH4 + (13 N-ammonium) efflux and retention data to analyse subcellular fluxes and compartmentation of NH4 + in the leaves of a higher plant (wheat, Triticum aestivum). • Leaf segments, 1-2mm, were obtained from 8-d-old seedlings. The viability of the segments, and stability of NH 4 + acquisition over time, were confirmed using oxygen-exchange and NH 4 + -depletion measurements. Fluxes of NH 4 + and compartment sizes were estimated using tracer efflux kinetics and retention data. • Influx and efflux across the plasma membrane, half-lives of exchange and cytosolic pool sizes were broadly similar to those in root systems. As the external concentration of NH 4 + ([NH 4 + ] o ) increased from 10µ m to 10m m , both influx and efflux greatly increased, with a sixfold increase in the ratio of efflux to influx. Half-lives were similar among treatments, except at [NH 4 + ] o =10m m , where they declined. Concentrations of NH 4 + in the cytosol ([NH 4 + ] c ) increased from 2.6 to 400m m . • Although [NH 4 + ] c became large as [NH 4 + ] o increased, the ratio of [NH 4 + ] c to [NH 4 + ] o decreased more than sixfold. The apparently futile cycling of NH 4 + at high [NH 4 + ] o suggested by the large fluxes of NH 4 + in both directions across the membrane indicate that leaf cells respond to potentially toxic NH 4 + concentrations in a manner similar to root cells.

Stepwise dehydrogenation of NH 3 at the Ru( [formula omitted]) surface

The thermal dehydrogenation of NH 3 was studied on Ru(1 1 2 ̄ 0) using high-resolution electron energy-loss spectroscopy and thermal desorption spectroscopy. Following NH 3 exposure at 85 K, the expected three dehydrogenation steps could be separated, allowing to isolate successively NH 2, NH and N on the surface. The Ru(1 1 2 ̄ 0) surface is highly reactive as indicated by the complete dehydrogenation of NH 3 for exposures up to 0.2 L. During annealing to 300 K both the channels for desorption and dehydrogenation are opened. Following adsorption at 85 K, the obtained nitrogen coverage of 0.11 ML is low, while for dissociative adsorption of NH 3 at 300 K, a maximum coverage of 0.38 ML is achieved, and the stability of NH 2 is increased.

Photoionization of hypervalent molecular clusters: electronic structure and stability of NH 4 (NH 3) n

Ammoniated NH 4 radicals produced by an ArF excimer laser photolysis of ammonia clusters are studied by one-photon ionization and time-of-flight mass spectroscopy. The ionization potentials (IPs) of NH 4(NH 3) n ( n = 0–35) are determined by the photoionization threshold measurements. The binding energies of NH 4 (NH 3) n−1 -NH 3 ( n = 1–6) are estimated from IPs. The results indicate that the bonding between NH 4 and NH 3 is semi-ionic. The IPs for larger clusters are found to decrease monotonically with increasing n to a limit of 1.33 eV, which coincides with the photoemission threshold of liquid NH 3. This feature is similar to those found recently for alkali atoms-ammonia clusters.

Electronic factors in chemisorption: NH 3 adsorption

In this paper experimental verification of the importance of electronic factors in determining the structure of chemisorbed species on various metals is presented. Furthermore, the modification of a single surface so as to change its chemisorption characteristics is demonstrated. Infrared spectra of NH 3 chemisorbed on vanadium and iron films at room temperature indicate adsorption occurs largely without dissociation. The NH 3 surface species are electron-donating with respect to the CO surface species. NH 3 does not adsorb in an undissociated form on our films of nickel and palladium. However adsorption of CO on these latter surfaces conditions them so that a NH 3 surface complex is stable. The stability of NH 3 on particular surfaces and its modification are explicable in terms of the electronic structure of the metal surface and a molecular orbital model of the bonding of NH 3 and CO to the metal surface.