CRYSTAL STRUCTURE OF A NEW HYDROLYSIS COMPLEX IN THE AQUEOUS ALUMINIUM SYSTEM. Magnus Karlsson, Dan Bostrom, Lars-Olof Ohman and Torbjorn Gustafsson* Department of Inorganic Chemistry, Umea University, S-901 87, Sweden, *Department of Inorganic Chemistry, University of Uppsala, S-751 21, Sweden

The chemistry of aluminium in aqueous solution is of great interest due to its toxic and deleterious environmental effects. The aluminiummonocarboxylic acid (HL) systems have been studied by means of potentiometric measurements^1,2. Data were mainly explained by the Al₂(OH)₂L³⁺complex. An attempt to crystallize this complex was made. Aluminium metal and aluminium chloride was dissolved in aqueous solutions of monocarboxylic acids to give solutions containing 0.6 M aluminium, 0.3 M monocarboxylic acid and a pH of around 3.7. After 6 to 12 months of slow evaporation in a refrigerator (6deg.C), transparent crystals appeared. The structure, solved by applying direct methods, did not contain the anticipated Al₂(OH)₂L³⁺ complex but a new hydrolysis complex with thirteen aluminium ions, that differed from the established [[epsilon]]-Keggin³ ion Al₁₃O₄(OH)₂₄(H₂O)₁₂⁷. The preliminary cell pararneters were a = 13.922 Å b = 23.572 Å c = 22.442 Å [[beta]] = 90.188deg. in the space group P2_l/c.

¹ E. Marklund, L.-O. Öhman and S. Sjöberg, Acta Chem. Scand., 43 1989) 641-646

² L.-O. Öhnan, Acta Chem. Scand., 45 (1991) 258-264

³ G. Johansson, Ark. Kemi, 20 (1963) 321