O-Phenylenedioxydiacetate complexes of Gd(III) and Ce(III): syntheses, crystal structures, and magnetic properties

Abstract

{[Ln2(PDOA)3(H2O)6]∙2H2O}n (Ln = Gd, 1; Ln = Ce, 2; H2PDOA = o-phenylenedioxydiacetic acid) has been synthesized and characterized by chemical analyses, IR spectroscopy, and thermal analyses. Single-crystal X-ray structure analyses revealed that both 1 and 2 are polymeric and built up of a ladder-like arrangement of Ln(III) ions linked by short syn-anti carboxylate bridges and long bridges (legs of the ladder) formed by a second crystallographically independent PDOA. Ln(III) in both 1 and 2 is nine-coordinate with an O9 donor set formed by one chelating/bridging and one bridging PDOA, and an additional three waters. In the asymmetric unit, there is one crystallographically independent water of crystallization, which is involved in a rich system of hydrogen bonds of the O–H···O type. The identities of the bulk and single crystal phases were corroborated by powder X-ray diffraction. Variable temperature (2–300 K) magnetic studies indicate the presence of only weak antiferromagnetic interactions between pairs of paramagnetic Ln(III) ions with J/hc = −0.004 and −0.13 cm−1, for 1 and 2.