Nuclear magnetic resonance study of hydrogen dynamics in Al(BH 4 ) 4 -based hypersalts M [Al(BH 4 ) 4 ] ( M = Na, K, Rb, Cs)
(2018) Journal of Alloys and Compounds — Vol. 745, n° 1, p. 179-186 (2018)
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Babanova-NuclearmagneticresonancestudyofhydrogendynamicsinAlBH44-basedhypersaltsMAlBH44MNaKRbCs.pdf
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- In order to study the dynamical properties of the novel series of complex hydrides M[Al(BH4)4] (M = Na, K, Rb, Cs), we have measured the ¹H and ¹¹B spin-lattice relaxation rates and the ¹H nuclear magnetic resonance spectra in these compounds over broad temperature ranges (6–384 K) and resonance frequency ranges (14–90 MHz). For all the studied compounds, the behavior of the spin-lattice relaxation rates is governed by the reorientational motion of BH4 groups. For Na[Al(BH4)4], the temperature dependences of the measured ¹H and ¹¹B spin-lattice relaxation rates suggest a coexistence of two reorientational processes with different characteristic jump rates and the activation energies of 186(7) and 262(9) meV. For K[Al(BH4)4], Rb[Al(BH4)4], and Cs[Al(BH4)4], the relaxation data are satisfactorily described by the model with a Gaussian distribution of the activation energies and the average activation energies of 393(6), 360(5), and 353(5) meV, respectively. The barriers for reorientational motion in M[Al(BH4)4] are discussed on the basis of changes in the local environment of BH4 groups.
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Babanova, O. A., Skoryunov, R. V., Soloninin, A. V., Dovgaliuk, I., Skripov, A. V., & Filinchuk, Y. (2018). Nuclear magnetic resonance study of hydrogen dynamics in Al(BH 4 ) 4 -based hypersalts M [Al(BH 4 ) 4 ] ( M = Na, K, Rb, Cs). Journal of Alloys and Compounds, 745(1), 179-186. https://doi.org/10.1016/j.jallcom.2018.02.201 (Original work published 2018)