One-dimensional cadmium(II)/bicinate(−1) complexes : The role of the alkali metal ion used in the reaction medium

Abstract

The initial employment of N,N-bis(2-hydroxyethyl)glycine (bicine; bicH3) in CdCl2 chemistry is reported, and the syntheses, IR spectra and crystal structures of the 1D coordination polymers [CdCl(bicH2)]n·nH2O (1·H2O) and [CdNaCl2(bicH2)(MeOH)]n (2) are described. The identity of the products depends on the solvent, the reaction temperature and the alkali metal ion of the base used. The structure of 1·H2O consists of zig-zag chains. The 7-coordinate CdII atoms are bridged by η1:η1:μ2 carboxylate groups of the 2.21111 (Harris notation) bicH2− ligand. The coordination geometry of the metal center can be either described as a very distorted pentagonal bipyramidal or as a distorted capped octahedral. In the structure of 2 the CdII atoms form an almost linear chain with neighboring NaI atoms on opposite sites of the chain. Every pair of CdII atoms is linked by two chloro ligands and the two oxygen atoms of the bicinate carboxylate group. The CdII and NaI atoms are bridged by one μ2 carboxylate bicinate oxygen and one μ3 chloro ligand. The 3.21,211121212 coordination mode of bicH2− is unprecedented. The CdCl4(Ocarboxylate)2 and Na(Ohydroxyl)2(Ocarboxylate)(OMeOH)NCl coordination spheres are octahedral and trigonal prismatic, respectively. IR data of the complexes are discussed in terms of the coordination modes of bicH2− and the known structures.