Structure and vibrational spectra of aluminum borohydride monoammine

Lobkovskii, É. B.; Polyakova, V.B.; Shilkin, S. P.; Семененко, К.Н.

doi:10.1007/bf00747551

Cited by 6 publications

(7 citation statements)

References 3 publications

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“…However, it should not be neglected that B−H bonds in BH 4 − are also very competitive with these metal cations to combine with NH 3 by the agency of N−H···H−B dihydrogen bonds. As one wildly existent bonding force between BH 4 − and NH 3 , for example, LiBH 4 NH 3 , Ca(NH 2 BH 3 ) 2 (NH 3 ) 2 , Mg(BH 4 ) 2 (NH 3 ) 2 , and Al(BH 4 ) 3 (NH 3 ) 6 , etc., it definitely plays a crucial role in determining the decomposition routes of MgCl 2 (NH 3 )/MBH 4 . So, M + and BH 4 − work together to attack the ligand NH 3 , and conversely, NH 3 can also join up to combine with BH 4 − .…”

Section: Resultsmentioning

confidence: 99%

The Comparison in Dehydrogenation Properties and Mechanism between MgCl₂(NH₃)/LiBH₄ and MgCl₂(NH₃)/NaBH₄ Systems

Gao

Guo

et al. 2010

J. Phys. Chem. C

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The dehydrogenation properties and mechanism of MgCl 2 (NH 3 )/MBH 4 (here, M is Li or Na) were investigated by thermogravimetric analysis and mass spectrometry, X-ray diffraction (XRD), solid-state 11 B NMR, Fourier transform infrared, and differential scanning calorimetry (DSC). As for the MgCl 2 (NH 3 )/LiBH 4 system, it was found that a new phase, namely, MgCl 2 (NH 3 ) • LiBH 4 , to which the following dehydrogenation relates, is formed after ball milling. Judging from the reaction products, it is confirmed that MgCl 2 is inclined to work as an ammonia carrier, and the ligand NH 3 , transferring from MgCl 2 , is able to combine with the LiBH 4 to release H 2 with a trace of ammonia at ca. 240 °C. With the increase of LiBH 4 content in the mixture, the emission of ammonia was totally suppressed, and Mg(BH 4 ) 2 was produced by the decomposition reaction of MgCl 2 with the excessive LiBH 4 after the ligand NH 3 was exhausted, resulting in an improved dehydrogenation in the whole system. As for the MgCl 2 (NH 3 )/NaBH 4 system, no new phases are detected by XRD after ball milling. The MgCl 2 works as a BH 4acceptor, and the ligand NH 3 stays with Mg 2+ to combine with the BH 4 -, which transfers from NaBH 4 to Mg 2+ , resulting in a totally different decomposition route and thermal effects as compared with the MgCl 2 (NH 3 )/LiBH 4 system. DSC results revealed that the decomposition of MgCl 2 (NH 3 )/LiBH 4 presented an exothermic reaction with an enthalpy of -3.8 kJ mol -1 H 2 , while the MgCl 2 (NH 3 )/NaBH 4 showed two apparent endothermic peaks associated with its two-step dehydrogenation with enthalpies of 8.6 and 2.2 kJ mol -1 H 2 , respectively. Moreover, the MS profiles of the MgCl 2 (NH 3 )/ 2NaBH 4 , with excessive BH 4 -, still released a trace of NH 3 , indicating that the NaBH 4 is not so effective in suppressing the emission of NH 3 as LiBH 4 did.

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Section: Resultsmentioning

confidence: 99%

The Comparison in Dehydrogenation Properties and Mechanism between MgCl₂(NH₃)/LiBH₄ and MgCl₂(NH₃)/NaBH₄ Systems

Gao

Guo

et al. 2010

J. Phys. Chem. C

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“…In Li 2 Al(BH 4 ) 5 ·6NH 3 , Al atoms are octahedrally coordinated exclusively by six NH 3 molecules with Al−N distance of 2.05 Å, longer than those in ammine aluminum halides such as Al(NH 3 ) 5 X 3 , Al(NH 3 ) 3 X 3 , Al(NH 3 ) 2 F 3 , Al(NH 3 )X 3 , and Al(NH 3 ) 6 Cl 6 (X = Cl, Br, and I) and also longer than those in Al(BH 4 ) 3 ·NH 3 . The Al−N distance(s) in these halides are in the range of 1.62−2.01 Å, and the Al−N distance in Al(BH 4 ) 3 ·NH 3 is 1.95 Å.…”

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confidence: 99%

“…The structure is illustrated in Figure 1a, the detailed crystallographic data are listed in Table S1, and the Rietveld fit to the diffraction pattern is shown in Figure S1. A noticeable feature of the Li 2 Al(BH 4 ) 5 3 6NH 3 structure is that each cation is coordinated completely by the same type of ligands, in contrast to the known monometallic borohydride ammoniates such as Li(NH 3 )BH 4 , 9,10 Mg(BH 4 ) 2 3 2NH 3 , 6 Ca(BH 4 ) 2 3 2NH 3 , 11 and Al(BH 4 ) 3 3 NH 3 , 18 where the cation is surrounded by both BH 4 and NH 3 groups. In Li 2 Al(BH 4 ) 5 3 6NH 3 , Al atoms are octahedrally coordinated exclusively by six NH 3 molecules with Al-N distance of 2.05 Å, longer than those in ammine aluminum halides such as Al-(NH 3 ) 5 X 3 , 19 Al(NH 3 ) 3 X 3 , 20 Al(NH 3 ) 2 F 3 , 21 Al(NH 3 )X 3 , 19 and Al(NH 3 ) 6 Cl 6 (X = Cl, Br, and I) 22 and also longer than those in Al(BH 4 ) 3 3 NH 3 .…”

mentioning

confidence: 99%

“…The structure is illustrated in Figure a, the detailed crystallographic data are listed in Table S1, and the Rietveld fit to the diffraction pattern is shown in Figure S1. A noticeable feature of the Li 2 Al(BH 4 ) 5 ·6NH 3 structure is that each cation is coordinated completely by the same type of ligands, in contrast to the known monometallic borohydride ammoniates such as Li(NH 3 )BH 4 , , Mg(BH 4 ) 2 ·2NH 3 , Ca(BH 4 ) 2 ·2NH 3 , and Al(BH 4 ) 3 ·NH 3 , where the cation is surrounded by both BH 4 − and NH 3 groups.…”

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confidence: 99%

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Dehydrogenation Tuning of Ammine Borohydrides Using Double-Metal Cations

et al. 2011

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The strategy of using double-cations to tune the temperature and purity of dehydrogenation of ammine borohydrides is reported. The first double-cation ammine borohydride, Li(2)Al(BH(4))(5)·6NH(3), which forms a novel structure with ordered arrangement of Al(NH(3))(6)(3+) ammine complexes and Li(2)(BH(4))(5)(3-) complex anions, is found to release over 10.0 wt % hydrogen below 120 °C with favorable kinetics and high H-purity (>99%).

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“…In particular, the reaction of Al(BH 4 ) 3 with one equivalent of NH 3 , NH 3 BH 3 or CH 3 NH 2 BH 3 gives molecular complexes [22,25,50]:…”

Section: Synthesis Of Molecular and Cation Alen And Aleb Complex Hydrmentioning

confidence: 99%

Aluminium complexes of B- and N-based hydrides: Synthesis, structures and hydrogen storage properties

Dovgaliuk

Filinchuk

2016

International Journal of Hydrogen Energy

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Structure and vibrational spectra of aluminum borohydride monoammine

Cited by 6 publications

References 3 publications

The Comparison in Dehydrogenation Properties and Mechanism between MgCl₂(NH₃)/LiBH₄ and MgCl₂(NH₃)/NaBH₄ Systems

The Comparison in Dehydrogenation Properties and Mechanism between MgCl₂(NH₃)/LiBH₄ and MgCl₂(NH₃)/NaBH₄ Systems

Dehydrogenation Tuning of Ammine Borohydrides Using Double-Metal Cations

Aluminium complexes of B- and N-based hydrides: Synthesis, structures and hydrogen storage properties

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Structure and vibrational spectra of aluminum borohydride monoammine

Cited by 6 publications

References 3 publications

The Comparison in Dehydrogenation Properties and Mechanism between MgCl2(NH3)/LiBH4 and MgCl2(NH3)/NaBH4 Systems

The Comparison in Dehydrogenation Properties and Mechanism between MgCl2(NH3)/LiBH4 and MgCl2(NH3)/NaBH4 Systems

Dehydrogenation Tuning of Ammine Borohydrides Using Double-Metal Cations

Aluminium complexes of B- and N-based hydrides: Synthesis, structures and hydrogen storage properties

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The Comparison in Dehydrogenation Properties and Mechanism between MgCl₂(NH₃)/LiBH₄ and MgCl₂(NH₃)/NaBH₄ Systems

The Comparison in Dehydrogenation Properties and Mechanism between MgCl₂(NH₃)/LiBH₄ and MgCl₂(NH₃)/NaBH₄ Systems