Nonasodium bis(hexahydroxoaluminate) trihydroxide hexahydrate (Na9[Al(OH)6]2(OH)3 · 6 H2O) - Crystal structure, NMR Spectroscopy and thermal behaviour

Article abstract of DOI:10.1002/zaac.19966221027

The crystal structure of the nonasodium bis(hexahydroxoaluminate) trihydroxide hexahydrate Na₉[Al(OH)₆]₂(OH)₃·6 H₂O (4.5 Na₂O·Al₂O₃·13.5 H₂O) (up to now described as 3 Na₂O·Al₂O₃·6 H₂O, 4 Na₂O·Al₂O₃· 13 H₂O and [3 Na₂O·Al₂O₃·6 H₂O][x NaOH·y H₂O], respectively) was solved. The X-ray single crystal diffraction analysis (triclinic, space group P1, a = 8.694(1) A, b = 11.344(2) A, c = 11.636(3) A, α = 74.29(2)°, β = 87.43(2)°, γ = 70.66(2)°, Z = 2) results in a structure, consisting of monomeric [Al(OH)₆]^3- aluminate anions, which are connected by NaO₆ octahedra groups. Furthermore the structure contains both, two hydroxide anions only surrounded by water of crystallization and OH groups of [Al(OH)₆]^3- aluminate anions and a hydroxide anion involved in three NaO₆ coordination octahedra directly and moreover connected with a water molecule by hydrogen bonding. The results of ²⁷Al and ²³Na-MAS-NMR investigations, the thermal behaviour of the compound and possible relations between the crystal structure and the conditions of coordination in the corresponding sodium aluminate solution are discussed as well. Johann Ambrosius Barth 1996.