Enhanced Effect of an External Electric Field on NH3BH3 Dehydrogenation: an AIMD Study for Thermolysis

How to improve the dehydrogenation properties of ammonia borane (AB, NH₃BH₃) is always a challenge for its practical application in hydrogen storage. In this study, we reveal the enhanced effect of an external electric field (E _ext) on AB dehydrogenation by means of the ab initio molecular dynamics method. The molecular rotation induced by an electrostatic force can facilitate the formation of the H-N···B-H framework, which would aggregate into poly-BN species and further suppress the generation of the volatile byproducts. Meanwhile, the dihydrogen bond (N-H^δ+···^δ-H-B) is favorably formed under E _ext, and the interaction between relevant H atoms is enhanced, leading to a faster H₂ liberation. Correspondingly, the apparent activation energy for AB dissociation is greatly reduced from 18.42 to around 15 kcal·mol^-1 with the application of an electric field, while that for H₂ formation decreases from 20.4 to about 16 kcal·mol^-1. In the whole process, the cleavage of the B-H bond is more favorable than that of the N-H bond, no matter whether the application of E _ext. Our results give a deep insight into a positive effect of an electric field on AB dehydrogenation, which would provide an important inspiration for hydrogen storage in industry applications.

The molecular structure, spectroscopic features and electronic properties of tioxolone under the external electric field

It is very helpful to understand the properties of molecules by studying a series of physical and chemical changes in molecules under an external electric field (EEF). Tioxolone is an important bioactive compound for its wide applications in the medical field. In this work, density function theory calculations combined with EEF were used to investigate the structure, spectra and electronic properties of tioxolone. The calculated results indicate that the bond lengths, bond angles, total energy, dipole moment, charge and aromaticity of tioxolone change under EEF. As EEF increases, the energy gap of tioxolone gradually reduces and makes it easier to participate in chemical reactions. Under the effect of EEF, the infrared and UV-Vis spectra show vibrational stark effect, which causes a redshift or blueshift of the frequency. These results help to understand the effect of EEF on structures and electronic properties for tioxolone, which will further provide effective guidance for the various application of tioxolone.

Realization of Lewis Basic Sodium Anion in the NaBH3 - Cluster

We report a Na:^- →B dative bond in the NaBH₃ ^- cluster, which was designed on the principle of minimum-energy rupture, prepared by laser vaporization, and characterized by a synergy of anion photoelectron spectroscopy and electronic structure calculations. The global minimum of NaBH₃ ^- features a Na-B bond. Its preferred heterolytic dissociation conforms with the IUPAC definition of dative bond. The lone electron pair revealed on Na and the negative Laplacian of electron density at the bond critical point further confirm the dative nature of the Na-B bond. This study represents the first example of a Lewis adduct with an alkalide as the Lewis base.