Hybrid open frameworks (MIL-n):: synthesis and crystal structure of MIL-17-a rare-earth dicarboxylate with a relatively open framework, [Pr(H2O)]2[O2C (CH2)2CO2]3•H2O

A new rare-earth dicarboxylate [Pr(H2O)](2)[O2C(CH2)(2)CO2](3). H2O (MIL-17) was hydrothermally prepared 180 degrees C, 3 days) by reaction of succinic acid with the metal chloride in the ratio 1:1. The crystal structure of the compound has been determined by single-crystal X-ray diffraction. [Pr(H2O)](2)[O2C(CH2)(2)CO2](3). H2O crystallizes in the monoclinic space group C2/c (No. 15) with a=20.2586 (8) Angstrom, b=7.9489(3) Angstrom, c=13.9716(5) Angstrom, beta=121.641(1)degrees (final agreement factors R-1=0.0282, wR(2)=0.0764). The organic-inorganic network is three-dimensional and consists of edge-sharing rare-earth polyhedra LnO(8)(H2O) chains linked together by the carbon chains along two directions as already encountered in [Pr(H2O)](2)[O2C(CH2)(3)CO2](3). 4H(2)O. The connection in [Pr(H2O)](2)[O2C(CH2)(2)CO2](3). H2O involves the formation of tunnels large enough to incorporate one weakly bonded water molecule. (C) 1999 Elsevier Science B.V. All rights reserved.