Composition of complex metal hydrides in polar solvents. I. Tertiary amines

Dilts, J. A.; Ashby, E. C.

doi:10.1021/ic50086a034

Cited by 15 publications

(16 citation statements)

References 3 publications

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“…Experimentally, Al−H frequencies in the 1750−1800 cm −1 range are typically associated with monomer complexes, while complexes possessing the bis structure have lower Al−H frequencies in the 1700−1750 cm −1 range, as do those of dimer complexes. 29 , 34 The G4(MP2) calculations confirm this. However, the predicted frequencies are systematically higher by 25−35 cm −1 , based on comparison with the measured gas-phase Al−H frequencies for monomer- and bis-TMAA 30 , 35 and monomer-DMEAA.…”

Section: Alane Complex Synthesis Characterization and Thermodynamicsupporting

confidence: 58%

“…Al-H frequencies in the 1700 -1750 cm -1 range, as do those of dimer complexes. 29,34 The G4(MP2) calculations confirm this. However, the predicted frequencies are systematically higher by 25 -35 cm -1 , based on comparison with the measured gas-phase Al-H frequencies for monomer-and bis-TMAA 30,35 and monomer-DMEAA.…”

Section: Alane Complex Synthesis Characterization and Thermodynamicssupporting

confidence: 56%

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Thermochemistry of Alane Complexes for Hydrogen Storage: A Theoretical and Experimental Investigation

et al. 2011

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Knowledge of the relative stabilities of alane (AlH3) complexes with electron donors is essential for identifying hydrogen storage materials for vehicular applications that can be regenerated by off-board methods; however, almost no thermodynamic data are available to make this assessment. To fill this gap, we employed the G4(MP2) method to determine heats of formation, entropies, and Gibbs free energies of formation for 38 alane complexes with NH3−nRn (R = Me, Et; n = 0−3), pyridine, pyrazine, triethylenediamine (TEDA), quinuclidine, OH2−nRn (R = Me, Et; n = 0−2), dioxane, and tetrahydrofuran (THF). Monomer, bis, and selected dimer complex geometries were considered. Using these data, we computed the thermodynamics of the key formation and dehydrogenation reactions that would occur during hydrogen delivery and alane regeneration, from which trends in complex stability were identified. These predictions were tested by synthesizing six amine−alane complexes involving trimethylamine, triethylamine, dimethylethylamine, TEDA, quinuclidine, and hexamine and obtaining upper limits of ΔG° for their formation from metallic aluminum. Combining these computational and experimental results, we establish a criterion for complex stability relevant to hydrogen storage that can be used to assess potential ligands prior to attempting synthesis of the alane complex. On the basis of this, we conclude that only a subset of the tertiary amine complexes considered and none of the ether complexes can be successfully formed by direct reaction with aluminum and regenerated in an alane-based hydrogen storage system.

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Section: Alane Complex Synthesis Characterization and Thermodynamicsupporting

confidence: 58%

Section: Alane Complex Synthesis Characterization and Thermodynamicssupporting

confidence: 56%

Thermochemistry of Alane Complexes for Hydrogen Storage: A Theoretical and Experimental Investigation

et al. 2011

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“…There is a well-known trend for tertiary amines to form 5 coordinate complexes with aluminium hydride. 16,30 When an excess amount of amine is present the ''bis'' type II structure is preferred. A 5 coordinate complex that possesses a ''bis'' structure would have Al-H stretch modes in the 1700-1750 cm À1 range.…”

Section: Dimethylethylamine Alanementioning

confidence: 99%

“…11,12 The heat of formation and the Gibbs free energy reported for the formation of a-AlH 3 from aluminium and hydrogen at room temperature suggest 7 Â 10 3 atm of pressurized hydrogen is necessary to form AlH 3 with aluminium. 12 The traditional method of producing alane is by synthesizing AlH 3 from LiAlH 4 and AlCl 3 using organic solvents, 1,[13][14][15][16] but this method produces stable salt byproducts that are costly to separate and therefore is not useful for many applications.…”

Section: Introductionmentioning

confidence: 99%

Regeneration of aluminium hydride using dimethylethylamine

Lacina

Wegrzyn

Reilly

et al. 2010

Energy Environ. Sci.

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“…7031 (3) 3325 (2) 925 (2) 69(1) C (9) 7702 (7) 3572 (6) 1787 (5) 124(3) C (10) 8411 (9) 4307 (7) 1571 (7) 184(5) C(ll) 8466 (7) 4377 (5) 556 (6) 140(4) C (12) 7546 (7) 3727 (5) 142 (5) 120 (3) 0(2) 1916 (3) 3585 (2) 5467 (3) 80(1) C (13) 7880 (6) 1171 (4) 1167 (5) 106(3) C (14) 8278 (6) 286 (4) 878 (5) 104(3) C (15) 8097 (6) 307 ( (14)). Tab.…”

Section: Diskussionunclassified

Lithium-dimethylamino-hydrido-aluminate: Lösungszustand in Diethylether, Tetrahydrofuran und Dimethyldiglykolether / Lithium Dimethylamino Hydrido Aluminates: The Solution State in Diethylether, Tetrahydrofuran and Dimethyldiglycol Ether

Bock

Nöth

1988

Zeitschrift Für Naturforschung B

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Abstract The reaction of LiAlH4 with dimethylamine has been studied in THF, diglyme and diethyl ether solution covering the molar ratios 1:0.5 to 1:4. In all cases the stoichiometric amount of H2 s evolved. With the exception of LiAl[N(CH3)2]4 all other members of the series LiAlH4-n[N(CH3)2]n cannot be isolated. They are in equilibrium with one another in solution, these equilibria are independent of the solvent used. The structure of compound LiAl[N(CH3)2]4 · 2(OC4H8) has been determined by X-ray diffraction. The anion acts as a bidentate ligand to Li which is also bonded to the oxygen atoms of two THF molecules.

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Composition of complex metal hydrides in polar solvents. I. Tertiary amines

Cited by 15 publications

References 3 publications

Thermochemistry of Alane Complexes for Hydrogen Storage: A Theoretical and Experimental Investigation

Thermochemistry of Alane Complexes for Hydrogen Storage: A Theoretical and Experimental Investigation

Regeneration of aluminium hydride using dimethylethylamine

Lithium-dimethylamino-hydrido-aluminate: Lösungszustand in Diethylether, Tetrahydrofuran und Dimethyldiglykolether / Lithium Dimethylamino Hydrido Aluminates: The Solution State in Diethylether, Tetrahydrofuran and Dimethyldiglycol Ether

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