γ-Zirconium and γ-titanium phosphate palladium intercalation compounds: synthesis and characterization by X-ray diffraction and thermal analyses

Abstract

γ-Zirconium and γ-titanium phosphates (γ-ZrP, γ-TiP) with layered structure are well known as ion exchangers as well as agents intercalating organic bases. In the latter case, the intercalation compounds may exchange transition metal ions coordinated by the ligands, giving rise to in situ formed complexes. We prepared phases derived from γ-ZrP, containing organic diamines (γ-ZrPL) (L = ligand), such as 2,2′-bipyridyl (bipy), 1,10-phenanthroline (phen), and 2,9-dimethyl-1,10-phenanthroline (dmp). These materials exchange Pd 2+ ions when they are in batch contact with a PdCl 2 solution and this produces solids with Pd 2+/L = 1. The X-ray diffraction (XRD) patterns of some materials containing Pd 2+ showed an increase of 2 Å in d 002. The differential thermal analysis (DTA) curves of the Pd 2+ materials showed a lowering of diamine temperature decomposition (100°C) with respect to those of their precursors. In the case of γ-TiP, we also obtained intercalation compounds with the above-mentioned diamines. Similar experiments showed that γ-TiPL exchanges very few Pd 2+ ions, except for the one derived from γ-TiPdmp. The thermogravimetric (TG) curves show the same lowering of ligand temperature decomposition for all materials except γ-TiPPdphen. The XRD patterns for all γ-ZrPPdL and γ-TiPPdL materials show peaks at d hkl = 7.89, 8.59–8.04, and 9.31 Å, for compounds containing Pdbipy, Pdphen, and Pddmp, respectively. Due to the correspondent complexes into the exchanger, these peaks disappeared when the materials, except for those containing the Pddmp complex, were stirred into CH 2Cl 2.