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In‐Situ and Real‐time Monitoring of Mechanochemical Preparation of Li 2 Mg(NH 2 BH 3 ) 4 and Na 2 Mg(NH 2 BH 3 ) 4 and Their Thermal Dehydrogenation
Author(s) -
Biliškov Nikola,
Borgschulte Andreas,
Užarević Krunoslav,
Halasz Ivan,
Lukin Stipe,
Milošević Sanja,
Milanović Igor,
Novaković Jasmina Grbović
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201702665
Subject(s) - bimetallic strip , raman spectroscopy , adduct , metal , chemistry , in situ , crystallography , crystal structure , single crystal , analytical chemistry (journal) , materials science , organic chemistry , physics , optics
Abstract For the first time, in situ monitoring of uninterrupted mechanochemical synthesis of two bimetallic amidoboranes, M 2 Mg(NH 2 BH 3 ) 4 (M=Li, Na), by means of Raman spectroscopy, has been applied. This approach allowed real‐time observation of key intermediate phases, and a straightforward follow‐up of the reaction course. Detailed analysis of time‐dependent spectra revealed a two‐step mechanism through MNH 2 BH 3 ⋅ NH 3 BH 3 adducts as key intermediate phases which further reacted with MgH 2 , giving M 2 Mg(NH 2 BH 3 ) 4 as final products. The intermediates partially take a competitive pathway toward the oligomeric M(BH 3 NH 2 BH 2 NH 2 BH 3 ) phases. The crystal structure of the novel bimetallic amidoborane Li 2 Mg(NH 2 BH 3 ) 4 was solved from high‐resolution powder diffraction data and showed an analogous metal coordination to Na 2 Mg(NH 2 BH 3 ) 4 , but a significantly different crystal packing. Li 2 Mg(NH 2 BH 3 ) 4 thermally dehydrogenates releasing highly pure H 2 in the amount of 7 wt.%, and at a lower temperature then its sodium analogue, making it significantly more viable for practical applications.