Stereodynamics study of the H′(²S) + NH(X³Σ⁻) → N(⁴S) + H₂reaction

Abstract

The stereodynamics and reaction mechanism of the H ( 2 S) + NH (X 3 Σ − ) → N( 4 S) + H 2 reaction are thoroughly studied at collision energies in the 0.1 eV-1.0 eV range using the quasiclassical trajectory (QCT) on the ground 4A potential energy surface (PES). The distributions of vector correlations between products and reagents P(θ r ), P(φ r ) and P(θ r , φ r ) are presented and discussed. The results indicate that product rotational angular momentum 𝑗 is not only aligned, but also oriented along the direction perpendicular to the scattering plane; further, the product H 2 presents different rotational polarization behaviors for different collision energies. Furthermore, four polarization-dependent differential cross sections (PDDCSs) of the product H 2 are also calculated at different collision energies. The reaction mechanism is analyzed based on the stereodynamics properties. It is found that the abstraction mechanism is appropriate for the title reaction.

Preparation, characterization, and properties of poly(thioether ether imide)s from isomeric bis(chlorophthalimide)s and 4,4′-thiobisbenzenethiol

“…Furthermore, the unsymmetrical units disturbed the regularity of molecular chain, which reduced the intermolecular interaction and hindered molecular chain close stacking, and therefore, the solvent molecules penetrate easily and the solubility increased. [24] Thermal properties of PTEIs…”

“…[11,12] There are two ways to synthesize isomeric polyimides, one is the polycondensation of isomeric tetracarboxylic dianhydrides and diamines, [11][12][13][14][15][16][17][18][19][20][21] the other is the nucleophilic displacements of isomeric bis(chlorophthalimide)s (BCPIs) with bisphenol or bisthiophenol. [22][23][24][25][26] In the first way, isomeric tetracarboxylic dianhydrides and diamines are commercially unavailable and need multi-steps to synthesize. In addition, tetracarboxylic dianhydrides tend to hydrolyze and diamines are easy to be oxidated in the process of preservation.…”

“…In the second way, isomeric BCPIs, bisphenol, or bisthiophenol are cheap, easy to access, air stable, and water tolerant. [23,24] What's more, the nucleophilicity of thiophenoxide is 100 times higher than that of phenoxide, which was reported in the synthesis of poly(thiother-ketone)s and poly(thioethersulfone)s. [27][28][29] The other main obstacle on the way to applications is poor hydrolytic stability of polyimides. Conventionally, it is believed that the carbonyl carbon atoms in aromatic imide ring are susceptible to the nucleophilic attack by water molecules, resulting in the degradation of the polymer main chains and a dramatic drop in the mechanical strength of polyimides.…”

“…[33] Flexible linkages -Oor -Scould be introduced into the polymer main chains via the nucleophilic displacements of BCPIs with bisphenol or bisthiophenol. [22][23][24][25][26] Meanwhile, thioether was generally more hydrophobic than the corresponding ether; thus, polymers with a higher content of thioether linkages would have less water absorption than the corresponding polymers containing ether linkages. [29,34] Therefore, polyimides containing flexible -Slinkages theoretically have good water stability.…”

“…Recently, our group have successfully synthesized isomeric poly(thioether ether imide)s (PTEIs) from isomeric BCPIs by aromatic nucleophilic substitution reaction. [23,24] Except solubility, thermal stability, and mechanical properties, the rules in hydrolytic stability and rheology properties of isomeric PTEIs had not been systematically studied before.…”