Infrared Spectra of the HAnX and H2 AnX2 Molecules (An=Th and U, X=Cl and Br) in Argon Matrices Supported by Electronic Structure Calculations

Cyanides, Isocyanides, and Hydrides of Zn, Cd and Hg from Metal Atom and HCN Reactions: Matrix Infrared Spectra and Electronic Structure Calculations

Zinc and cadmium atoms from laser ablation of the metals and mercury atoms ablated from a dental amalgam target react with HCN in excess argon during deposition at 5 K to form the MCN and MNC molecules and CN radicals. UV irradiation decreases the higher energy ZnNC isomer in favor of the lower energy ZnCN product. Cadmium and mercury atoms produce analogous MCN primary molecules. Laser ablation of metals also produces plume radiation which initiates H‐atom detachment from HCN. The freed H atom can add to CN radical to produce the HNC isomer. The argon matrix also traps the higher energy but more intensely absorbing isocyanide molecules. Further reactions with H atoms generate HMCN and HMNC hydrides, which can be observed by virtue of their C−N stretches and intense M−H stretches. Computational modeling of IR spectra and relative energies guides the identification of reaction products by providing generally reliable frequency differences within the Zn, Cd and Hg family of products, and estimating isotopic shifts using to ¹³C and ¹⁵N isotopic substitution for comparison with experimental data.

Nitrogen-rich covalent organic frameworks with multiple carbonyls for high-performance sodium batteries

Covalent organic frameworks with designable periodic skeletons and ordered nanopores have attracted increasing attention as promising cathode materials for rechargeable batteries. However, the reported cathodes are plagued by limited capacity and unsatisfying rate performance. Here we report a honeycomb-like nitrogen-rich covalent organic framework with multiple carbonyls. The sodium storage ability of pyrazines and carbonyls and the up-to twelve sodium-ion redox chemistry mechanism for each repetitive unit have been demonstrated by in/ex-situ Fourier transform infrared spectra and density functional theory calculations. The insoluble electrode exhibits a remarkably high specific capacity of 452.0 mAh g-1, excellent cycling stability (~96% capacity retention after 1000 cycles) and high rate performance (134.3 mAh g-1 at 10.0 A g-1). Furthermore, a pouch-type battery is assembled, displaying the gravimetric and volumetric energy density of 101.1 Wh kg-1cell and 78.5 Wh L-1cell, respectively, indicating potentially practical applications of conjugated polymers in rechargeable batteries.

Matrix Infrared Spectra, Photochemistry and Density Functional Calculations of Cl--HCCl2, ClHCl-, Cl-ClCCl, and Cl--HCHCl Produced from CHCl3 and CH2Cl2 Exposed to Irradiation from Laser Ablation

Strong absorptions for Cl^--HCCl₂ with D and ¹³C isotopes were observed in the spectra of CHCl₃ codeposited with laser-ablated metal atoms, cations, electrons, and vacuum ultraviolet radiation, which shows that the precursor is an effective electron scavenger. The IR spectra, isotopic shifts, and DFT calculations identified the major product as Cl^--HCCl₂, which is characterized by a strong, broad C-H stretching mode interacting with the overtone of the H-C-Cl bending fundamental. These absorptions decreased on subsequent annealing and photolysis treatments while the ClHCl^- absorptions increased, suggesting that dissociation of the chloroform anion generates the stable symmetrical hydrogen dichloride anion as does the reaction of HCl and Cl^-. A new set of strong, broad absorptions in the deposition spectra that diminished on the early annealing and photolysis are assigned to the Cl-ClCCl radical isomer. Dominant spectral features in the C-H stretching region for the experiments with CH₂Cl₂ are assigned to the symmetric C-H and the antisymmetric Cl-H-C-H stretching bands of the methylene chloride anion Cl^--HCHCl. The stronger, broader, lower frequency bands are due to the hydrogen-bonded hydrogen stretching, and the weaker, sharper, higher frequency absorptions are due to the terminal C-H bond stretching. Similar experiments with CHBr₃ produced absorptions for the analogous Br^--HCBr₂ and BrHBr^- anions.