New open-framework three-dimensional lanthanide oxalates containing as a template the diprotonated 1,2- or 1,3-diaminopropane

Single crystals of three new open-framework lanthanide oxalates have been synthesized hydrothermally, in the presence of 1,2-diaminopropane, (C3N2H12)[Nd(H2O)(C2O4)(2)](2)center dot 3H(2)O I and (C3N2H12)[Yb(C2O4)(2)](2)center dot 5H(2)O II, or 1.3-diaminopropane (C3N2H12)(2) [La-2(C2O4)(5)]center dot 5H(2)O III. Their structures have been determined by X-ray diffraction data: I and III crystallize in the triclinic system, space group P-1, with a = 7.8130(5) angstrom, b = 11.8800(6) angstrom, c = 12.9940(8) angstrom, alpha = 93.092(5)degrees, beta = 93.930(6)degrees, gamma = 108.359(5)degrees and a = 11.6650(9) angstrom, b = 11.9240(6) angstrom, c = 13.2230(7) angstrom, alpha = 104.585(4)degrees, beta = 108.268(5)degrees, gamma = 111.132(5)degrees, respectively while II crystallizes in the orthorhombic system, space group F2dd, with a = 8.7970(4) angstrom, b = 16.1550(8) angstrom, c = 32.170(2) angstrom. The three-dimensional (3D) framework of these compounds is built up by the linkages of lanthanide atoms and the oxygen atoms of the bischelating oxalate ligands. Instead of four chelating oxalate units surrounding a lanthanide atom (I and II), both lanthanum atoms, in III, are surrounded by five chelating oxalate groups and that is new. In all the cases within the frame, are observed 8- and 12-membered channels where are localized the guest species, 1,2- or 1,3-diaminopropane cations and free water molecules. The ratio of the guest number (especially the diaminopropane) per 12-membered ring could tune the shape and the size of 12-membered channels: thus, the 12-inembered channels, observed for I and II, have elliptical cross-section (5.5 angstrom x 11.4 angstrom and 5.2 angstrom x 9.5 angstrom) while those, observed for III, have nearly circular cross-section (9.1 angstrom x 9.5 angstrom). The lanthanide atoms are 8, 9 and 10-fold coordinated for Yb (II). Nd (I) and La (III), respectively. (c) 2005 Elsevier Inc. All rights reserved.