Towards hydrogen-rich ionic (NH4)(BH3NH2BH2NH2BH3) and related molecular NH3BH2NH2BH2NH2BH3

TL;DR

This study explores the synthesis, characterization, and hydrogen release properties of an ionic compound and related molecules containing high hydrogen content, revealing challenges with impurities during hydrogen release.

Contribution

It reports the synthesis and structural analysis of an ionic hydrogen-rich compound and its molecular analog, highlighting their hydrogen release behavior and associated impurities.

Findings

Successful synthesis and structural determination of the ionic compound and molecular analog.

Both compounds release hydrogen with impurities like borazine, ammonia, and diborane.

The compounds exhibit high hydrogen content but face challenges with impurity pollution during hydrogen release.

Abstract

Attempts of synthesis of ionic (NH4)(BH3NH2BH2NH2BH3) using metathetical approach resulted in a mixture of the target compound and a partly dehydrogenated molecular NH3BH2NH2BH2NH2BH3 product. The mixed specimen was characterized by NMR and vibrational spectroscopies, and the crystal structure of their cocrystal was solved from powder x-ray diffraction data, and supplemented by theoretical density functional theory calculations. Despite their impressive hydrogen content, and similarly to ammonia borane, both title compounds release hydrogen substantially polluted with borazine, and traces of ammonia and diborane.