Molecular Dynamics Simulation of the Solid-State Topochemical Polymerization of S2N2

Direct Visualization of Chemical Transport in Solid-State Chemical Reactions by Time-of-Flight Secondary Ion Mass Spectrometry

Systematic control and design of solid-state chemical reactions are required for modifying materials properties and in novel synthesis. Understanding chemical dynamics at the nanoscale is therefore essential to revealing the key reactive pathways. Herein, we combine focused ion beam-scanning electron microscopy (FIB-SEM) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) to track the migration of sodium from a borate coating to the oxide scale during in situ hot corrosion testing. We map the changing distribution of chemical elements and compounds from 50 to 850 °C to reveal how sodium diffusion induces corrosion. The results are validated by in situ X-ray diffraction and post-mortem TOF-SIMS. We additionally retrieve the through-solid sodium diffusion rate by fitting measurements to a Fickian diffusion model. This study presents a step change in analyzing microscopic diffusion mechanics with high chemical sensitivity and selectivity, a widespread analytical challenge that underpins the defining rates and mechanisms of solid-state reactions.

FP(μ-N)2 S: A Sulfur-Pnictogen Four-Membered Ring with 6π Electrons

The new 6π-electron four-membered ring compound 3-fluoro-1λ2 ,2,4,3λ3 -thiadiazaphosphetidine, FP(μ-N)2 S, has been generated in the gas phase through high-vacuum flash pyrolysis (HVFP) of thiophosphoryl diazide, FP(S)(N3 )2 , at 1000 K. Subsequent isolation of FP(μ-N)2 S in cryogenic matrices (Ar, Ne, and N2 ) allows its characterization with matrix-isolation IR and UV-vis spectroscopy by combination with 15 N-isotope labeling and computations at the CCSD(T)-F12a/VTZ-F12 level of theory. Upon visible-light irradiation at 550 nm, this cyclic compound undergoes ring-opening to the thiazyl isomer FPNSN, followed by dissociation to FP and SN2 under subsequent UV-irradiation at 365 nm. In sharp contrast to the square planar structure for the isolobal four-membered ring S2 N2 , a puckered structure with significant biradical character has been found for FP(μ-N)2 S.

Neutral binary chalcogen-nitrogen and ternary S,N,P molecules: new structures, bonding insights and potential applications

Early theoretical and experimental investigations of inorganic sulfur-nitrogen compounds were dominated by (a) assessments of the purported aromatic character of cyclic, binary S,N molecules and ions, (b) the unpredictable reactions of the fascinating cage compound S4N4, and (c) the unique structure and properties of the conducting polymer (SN)x. In the last few years, in addition to unexpected developments in the chemistry of well-known sulfur nitrides, the emphasis of these studies has changed to include nitrogen-rich species formed under high pressures, as well as the selenium analogues of well-known S,N compounds. Novel applications have been established or predicted for many binary S/Se,N molecules, including their use for fingerprint detection, in optoelectronic devices, as high energy-density compounds or as hydrogen-storage materials. The purpose of this perspective is to evaluate critically these new aspects of the chemistry of neutral, binary chalcogen-nitrogen molecules and to suggest experimental approaches to the synthesis of target compounds. Recently identified ternary S,N,P compounds will also be considered in light of their isoelectronic relationship with binary S,N cations.

A synthetic co-crystal prepared by cooperative single-crystal-to-single-crystal solid-state Diels–Alder reaction

Solid-state Diels–Alder reaction in a 2 : 1 donor to acceptor charge-transfer complex leads to a synthetic co-crystal composed of product and unreacted donor. Analysis of close contacts and DFT energy calculations indicate that the reaction occurs cooperatively where the arrangement of molecules shown in (ii) is favoured.

Breathing some new life into an old topic: chalcogen-nitrogen π-heterocycles as electron acceptors

Recent progress in the design, synthesis and characterization of chalcogen-nitrogen π-heterocycles, mostly 1,2,5-chalcogenadiazoles (chalcogen: S, Se and Te) and their fused derivatives, possessing positive electron affinity is discussed together with their use in preparation of charge-transfer complexes and radical-anion salts-candidate building blocks of molecule-based electrical and magnetic functional materials.