1-D and 2-D Coordination Polymers of Cerium(III) With Pyridine-2,4,6-Tricarboxylic Acid: Synthesis and Structural, Spectroscopic, and Thermal Properties

Abstract

Two new Ce(III) complexes of pyridine-2,4,6-tricarboxylate (ptc), [Ce <inf>2</inf>(H <inf>2</inf>O) <inf>2</inf>(C <inf>8</inf>H <inf>3</inf>NO <inf>6</inf>) <inf>4</inf>(C <inf>2</inf>O <inf>4</inf>)Na <inf>2</inf>(H <inf>2</inf>O) <inf>5</inf>] <inf>n</inf> (H <inf>2</inf>O) <inf>4</inf> (1) and [Ce(H <inf>2</inf>O) <inf>3</inf>(C <inf>8</inf>H <inf>2</inf>NO <inf>6</inf>)] <inf>n</inf> (H <inf>2</inf>O) (2), were crystallized in the triclinic space group P-1 and the monoclinic space group P <inf>21</inf>/c, respectively. These polymers were also characterized by elemental analysis, FTIR spectroscopy, and thermogravimetric analysis. The latter shows high thermal stability for 1. Each Ce(III) is ten-coordinate with two nitrogen atoms from two pyridine rings, five oxygen atoms from five carboxylic groups, two oxygen atoms from oxalate and one oxygen from water. Oxygen at the 2,6-position of ptc is a bridge to construct a 1-D polymer for 1. Each Ce(III) is nine-coordinate with five oxygen atoms and one nitrogen from ptc and three water molecules, giving a tricapped trigonal prism for 2. Each ptc bridges three Ce(III) ions with the formation of 2-D polymeric chains, and each carboxylic acid group at the 2,6-position of ptc is only bound to one Ce(III). The other carboxylate at the 6-position is bound to another Ce(III), and the carboxylates at the four-position adopt a chelating mode. Molecules are linked principally by OHO hydrogen bonds involving water and carboxylate, forming R <inf>2</inf> 1(6),R <inf>3</inf> 3 (14), and R <inf>4</inf> 4(27) rings, which link to give a 3-D network. © 2012 Taylor & Francis.