Novel inorganic coordination polymers based on cadmium oxalates

摘要

Three new cadmium oxalate coordination polymers, I-III, with extended layered structures have been synthesized in the presence of imidazole. While I was prepared by the reaction between imidazolium oxalate and Cd, II and III were synthesized from their constituents using hydrothermal methods. [Cd(C2O4)(C3N2H4)](infinity) (I): monoclinic, space group P2(1)/c (no. 14), a = 8.7093(l) Angstrom, b = 9.9477(3) Angstrom, c = 8.4352 A, beta = 93.796(1)degrees, Z = 4; [Cd(C2O4)(2)(C3N2H4)(3)(H2O)]infinity (II): monoclinic, space group P2(1)/c (no. 14), a = 7.8614(2) Angstrom, b = 14.9332(3) Angstrom, c = 15.9153(4) Angstrom, beta = 94.587(l)degrees, Z = 4; [Cd(C2O4)(2)(C3N2H4)(3)(H2O)]infinity. (III): monoclinic, space group P2(1)/c (no. 14), a = 11.844(2) Angstrom, b = 9.066(l) Angstrom, c = 18.583(2) Angstrom, P = 103.84(2)degrees, Z = 4. While the structure of I is made from CdO5N distorted octahedra linked with oxalate, II and III are built-up from CdO6N, CdO5N2 distorted pentagonal bi-pyramids connected to oxalate units. The framework formulas of II and III are identical and their structures closely related. In all the cases, the networking between the Cd-O/N polyhedra and oxalates give rise to layered architectures with the amine molecules pointing in a direction perpendicular to the layers (in the inter-lamellar region). The difference in the linkages between the oxalates and the Cd atoms in I-III, produces unusual Cd-O-Cd one-dimensional chains, which have been observed for the first time. (C) 2002 Elsevier Science (USA). [References: 49]