SYNTHESES AND CRYSTAL-STRUCTURES OF ALPHA-METHYL ALANINIUM DIHYDROGEN MONOPHOSPHATE AND L-BETA METHYL ALANINIUM DIHYDROGEN MONOPHOSPHATE - AN APPROACH FOR THE DESIGN AND PREPARATION OF POLAR ORGANIC-INORGANIC MATERIALS

The two following salts have been prepared [(CH3)2C(NH3)-COOH]+ H2PO4 (aMADP) and [CH3CH2CH(NH3)COOH] + ” H2PC>4 (LßMADP). The crystal parameters are: a = 10.060(2), b = 7.634(2), c = 5.852(2) A, a = 97.32 °(5), ß = 107.50 °(5), y - 81.16°(5); Z = 2; PI for aMADP and a - 7.164(2), b - 6.533(2), c = 9.458(2) Ǻ; ß = 105.48°(7); Z = 2; P2i for LßMADP. Crystal structures were solved by direct methods and refined to a final R value 0.026 with 2889 independent data for aMADP and to R ” 0.033 with 2027 reflexions for LßMADP. Hydrogen atoms located by difference-Fourier syntheses were refined. The layer structure of aMADP and the chain structure of LMADP emphasize the importance of H2PO4 polymeric anion and its possible use in the design of polar inorganic materials. The effect of chirality on the anion-aggregation, through the hydrogen bonds, clearly indicated by the LßMADP structure and some others already described, may be easily transposed to individual, cylic, chain or layer inorganic oxoanions. © 1990, Walter de Gruyter