The two following salts have been prepared [(CH3)2C(NH3)-COOH]+ · H2PO4− (αMADP) and [CH3CH2CH(NH3)COOH]+ · H2PO4− (LβMADP). The crystal parameters are: a = 10.060(2), b = 7.634(2), c = 5.852(2) Å, α = 97.32°(5), β = 107.50°(5), γ = 81.16°(5); Z = 2; P[unk] for αMADP and a = 7.164(2), b = 6.533(2), c = 9.458(2) Å; β = 105.48°(7); Z = 2; P21 for LβMADP. Crystal structures were solved by direct methods and refined to a final R value 0.026 with 2889 independent data for αMADP and to R = 0.033 with 2027 reflexions for LβMADP. Hydrogen atoms located by difference-Fourier syntheses were refined. The layer structure of αMADP and the chain structure of LβMADP 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 LβMADP structure and some others already described, may be easily transposed to individual, cylic, chain or layer inorganic oxoanions.
Lead tetrasodium trimetaphosphate PbNa4(P3O9)2 is triclinic, P[unk] with a = 7.268(4), b = 8.151(5), c = 7.851(5) Å, α = 121.52(5), β = 102.06(5), γ = 73.00(5)°, Z = 1, V = 378.3 Å3 and dx = 3.393 g/cm3. Its crystal structure has been solved using 1507 reflexions, with a final R value 0.049 for 1268 reflexions. The atomic arrangement is characterized by a disorder between Pb and Na on one crystallographic site. Chemical preparation and crystal data are given for the isotypic barium salt: BaNa4(P3O9)2.