Hydrothermal synthesis, X¿ray structure and DFT and magnetic studies of a novel (H2SiW12O40)2¿ based one¿dimensional linear coordination polymer via in situ transformation of pyridine¿2,3¿dicarboxylic acid into nicotinic and 2¿hydroxynicotinic acids

Abstract

[eng] In this paper, we report the synthesis and characterization of a novel hybrid with an inorganic-organic structure formulated as [[Nd2(L1)2(L2)(H2O)7][H2SiW12O40]]n·4H2O (1), in which HL1 = nicotinic acid and H2L2 = 2-hydroxynicotinic acid. Interestingly, L1 and L2 are generated from an in situ transformation of the original ligand, pyridine-2,3-dicarboxylic acid under hydrothermal conditions. Structural analysis showed that this compound is a one-dimensional linear coordination polymer constructed from a repetition of the Keggin anion as a bidentate bridging ligand and one propeller-like dinuclear neodymium complex. Furthermore, in the packing arrangement, hydrogen bonds and anion-π interactions connect the adjacent chains to extend the structure into a 3D architecture. The magnetic properties of this compound have also been studied by measuring its magnetic susceptibility in the temperature range 1.8-300 K. We also analyzed the coordination ability of the SiW12 Keggin anion in the reported structures up to now. Finally, we have performed a DFT computational study on the noncovalent anion-π interactions between the Keggin anion and the aromatic ligands coordinated to Nd