Evidence of 13 hybrid fluoroaluminates in the composition space diagram of the Al(OH)3-tren-HF-ethanol system

Thirteen phases are now evidenced in the composition space diagram of the Al(OH)(3)-tren-HF-ethanol system at 190 degrees C. Solvothermal syntheses are performed under microwave heating. Six new organic-inorganic fluorides crystallise and their structures are determined: (H3O)center dot[H(4)tren](2)center dot(AlF6)(3)center dot 6H(2)O (P-1, Z=2), [H(3)tren](2)center dot(AlF5(H2O))(3)center dot 8H(2)O (C2/c, Z=8), [H(3)tren](4)center dot(AlF6)(2)center dot(Al2F11)center dot(F)center dot 10H(2)O (P2(1)/n, Z=2), [H(3)tren](2)center dot(Al4F18)center dot 3.5H(2)O (P6(3), Z=2), [H(3)tren](2)center dot(Al4F18) (P-1, Z=1), and [H(3)tren](4)center dot(Al8F35)center dot(OH)center dot H2O (P-1, Z=1). The existence domains are approximately located for all phases. Tren amine is tetra protonated at high HF concentration, otherwise it is triprotonated. A protonated water cluster, H3O*(H2O)(6),appears in (H3O)center dot[H(4)tren](2)center dot(AlF6)(3)center dot 6H(2)O while a new Al4F18 unit, found in [H(3)tren](2)center dot(Al4F18), is evidenced: it results from corner and edge sharing association of four AlF6 octahedra. Finally, the structure of [H(3)tren](4)center dot(Al8F35)center dot(OH)center dot H2O revealed the largest known fluoroaluminate polyanion, built from eight vertex sharing AlF6 octahedra, (Al8F35)(11-). (C) 2009 Elsevier B.V. All rights reserved.