From solutions containing praseodymium perchlorate and periodic acid, three different modifications of [Pr-2(ClO4)(2)(H2I2O10)] . 8 H2O could be obtained. All of them crystallize in the monoclinic system, space group P2(1)/c (alpha: a = 1091.47(6), b = 728.24(4), c = 1388.84(8) pm, beta = 101.420(3)degrees; beta: a = 1169.93(3), b = 728.72(2), c = 1384.50(4) pm, beta = 112.303(2)degrees; gamma: a = 1209.56(4), b = 712.53(2), c = 1361.64(5) pm, beta = 115.691(1)degrees). The structures contain Pr3+ cations which are coordinated by [H2I2O10](4-) anions yielding two-dimensional networks. These networks are separated by ClO4- anions yielding a layered structure.
QC 20100525 QC 20111031