Tetrahydrofurantetracarboxylic Acid: An Isomerizable Framework-Forming Ligand in Homo- and Heterometallic Complexes with UO22+, Ag+, and Pb2+

Abstract

(2R*,3R*,4S*,5S*)-Tetrahydrofurantetracarboxylic acid (H4thftc) has been used as a ligand to synthesize five uranyl ion complexes, three of them including additional silver(I) or lead(II) metal cations. The complex [C(NH2)3]2[UO2(H2thftc)2] (1), obtained in water at room temperature, is a discrete mononuclear species in which the uranyl cation is bound to the tridentate coordination site (involving the ether oxygen atom and the two adjoining carboxylate groups) of two ligands, and extensive hydrogen bonding is present. All the other complexes were obtained under (solvo)-hydrothermal conditions giving rise to higher degrees of ligand deprotonation. [(UO2)3(Hthftc)2(H2O)2]·2CH3CN (2) crystallizes as a two-dimensional (2D) network with the V2O5 topological type, whereas in the heterometallic complex [(UO2)3Ag2(thftc)2(H2O)2]·2H2O (3), similar 2D layers are assembled into a three-dimensional (3D) framework by bridging Ag2 moieties. Lead(II) replaces uranyl in the tridentate coordination site in the two comple...