Synthesis, Structural Characterization, and Hydrogen Release of Al-Based Amidoboranes Derived from MAlH<sub>4</sub> (Li, Na)-BH<sub>3</sub>NH<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>NH<sub>2</sub>BH<sub>3</sub>

Over the past two decades, the high hydrogen content and favorable dehydrogenation conditions of multi-metallic amidoboranes have gained significant attention for their potential in hydrogen storage. Among them, Al-based complex hydrides have shown promise because of their high polarizing power, lig...

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Main Authors: Ting Zhang, Xiao Li, Hai-Wen Li, Michel Devillers, Yaroslav Filinchuk
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/30/7/1559
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Summary:Over the past two decades, the high hydrogen content and favorable dehydrogenation conditions of multi-metallic amidoboranes have gained significant attention for their potential in hydrogen storage. Among them, Al-based complex hydrides have shown promise because of their high polarizing power, light weight, and abundant natural presence. In this work, we successfully synthesized two novel tetrahedrally coordinated Al-based amidoboranes, namely, Li[Al(BH<sub>3</sub>NHCH<sub>2</sub>CH<sub>2</sub>NHBH<sub>3</sub>)<sub>2</sub>] and Na(THF)[Al(BH<sub>3</sub>NHCH<sub>2</sub>CH<sub>2</sub>NHBH<sub>3</sub>)<sub>2</sub>], using BH<sub>3</sub>NH<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>NH<sub>2</sub>BH<sub>3</sub> (EDAB) as a precursor. The structure of Na(THF)[Al(BH<sub>3</sub>NHCH<sub>2</sub>CH<sub>2</sub>NHBH<sub>3</sub>)<sub>2</sub>] was determined through modeling based on synchrotron powder X-ray diffraction. Additionally, the formation of the Al-N bond in Li[Al(BH<sub>3</sub>NHCH<sub>2</sub>CH<sub>2</sub>NHBH<sub>3</sub>)<sub>2</sub>] and Na(THF)[Al(BH<sub>3</sub>NHCH<sub>2</sub>CH<sub>2</sub>NHBH<sub>3</sub>)<sub>2</sub>] was confirmed with IR spectra. Na(THF)[Al(BH<sub>3</sub>NHCH<sub>2</sub>CH<sub>2</sub>NHBH<sub>3</sub>)<sub>2</sub>] is more stable in air than Li[Al(BH<sub>3</sub>NHCH<sub>2</sub>CH<sub>2</sub>NHBH<sub>3</sub>)<sub>2</sub>]. Importantly, thermal gravimetric analysis and mass spectroscopic characterization confirmed that both compounds release hydrogen without the presence of ammonia, diborane, or ethylenediamine. Our work represents the first example of Al-based amidoboranes with chelation coordination geometry, which provides an essential foundation for understanding the relationship of complex multi-metallic amidoboranes in terms of synthesis, structure, and properties.
ISSN:1420-3049