The results show that the DEE and THF adducts of calcium
tetrahydroaluminate can be prepared by ball milling under
inert conditions or by mechanically assisted wet-chemical
synthesis. For each process, the same metathesis reaction 2
can be applied. After separation from the byproduct by digesttion
or Soxhlet extraction, the organic solvent can be removmoved
almost completely in a drying procedure under vacuum
at elevated temperatures. Thus, gram amounts of calcium
tetrahydroaluminate with a purity of >90% are obtained.
Of the alkaline-earth-metal tetrahydroaluminates, the
lighter Mg(AlH4)2 exhibits a sheet structure consisting of
octahedrally coordinated Mg atoms interconnected by tetrahedral
[AlH4] groups.3 BaAlH5 as the next heavier compound
after calcium tetrahydroaluminate contains onedimensional
zigzag chains of distorted [AlH6] octahedra.12
Sr2AlD7 structurally contains edge-sharing [DSr4] tetrahedra
as well as isolated [AlD6] octahedra.13 In the case of calcium
tetrahydroaluminate, IR data and the mass balance, including
the impurities, such as NaCl and residual organic solvent,
suggest a compound with the composition of Ca(AlH4)2
similar to Mg(AlH4)2. The IR data did not indicate any
formation of a hexahydride or pentahydride structure.
Moreover, a partial decomposition would be required for the
formation of a pentahydride from the isolated Ca(AlH4)2â4THF
according to
The results show that the DEE and THF adducts of calciumtetrahydroaluminate can be prepared by ball milling underinert conditions or by mechanically assisted wet-chemicalsynthesis. For each process, the same metathesis reaction 2can be applied. After separation from the byproduct by digesttionor Soxhlet extraction, the organic solvent can be removmovedalmost completely in a drying procedure under vacuumat elevated temperatures. Thus, gram amounts of calciumtetrahydroaluminate with a purity of >90% are obtained.Of the alkaline-earth-metal tetrahydroaluminates, thelighter Mg(AlH4)2 exhibits a sheet structure consisting ofoctahedrally coordinated Mg atoms interconnected by tetrahedral[AlH4] groups.3 BaAlH5 as the next heavier compoundafter calcium tetrahydroaluminate contains onedimensionalzigzag chains of distorted [AlH6] octahedra.12Sr2AlD7 structurally contains edge-sharing [DSr4] tetrahedraas well as isolated [AlD6] octahedra.13 In the case of calciumtetrahydroaluminate, IR data and the mass balance, includingthe impurities, such as NaCl and residual organic solvent,suggest a compound with the composition of Ca(AlH4)2similar to Mg(AlH4)2. The IR data did not indicate anyformation of a hexahydride or pentahydride structure.Moreover, a partial decomposition would be required for theformation of a pentahydride from the isolated Ca(AlH4)2â4THFaccording to
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