Structural Variations in Coordination Polymers of Sodium and Cesium Dicarboxylates

Abstract

The coordination polymer {[Na2L(μ-H2O)(H2O)3]·H2O}n (1) derived from 2,2′-(phenylmethylidene-bis(3,5-methyl-2-phenyleneoxy)] diacetic acid (H2L) has repeat units comprising of hexa-coordinate diaqua-bridged dinuclear sodium complex ions. These units are connected through intervening mononuclear complex parts having penta-coordinated sodium ions. The sodium ions adopt repeated hexameric chair-like arrangement in the polymer. The cesium salt of H2L namely [Cs(HL)(μ-H2O)(H2O)]n (2) is a coordination polymer. In this case one acid group of the ligand is deprotonated and 2 form self-assembly by intermolecular hydrogen bonds between the free carboxylic acid groups. The fluoro-substituted ligand 2,2′-(2-fluorophenylmethyledene-bis(3,5-methyl-2-phenyleneoxy)] diacetic acid (H2Lf) forms disodium salt with a composition [{Na2Lf(μ-H2O)(H2O)3}·H2O]n (3); which is a two dimensional coordination polymer. On the other hand the corresponding cesium salt of H2Lf has a composition [{(H2O)Cs(μ-H2O)(μ-Lf)Cs(H2O)2}] (4); which is also a 2-D coordination polymer. The cesium ions are six or nine coordinate in the polymer and the coordination polymer possesses unusual Cs···F–C coordination bond.