Co-ordination of alkali metals by open-chain polyethers in transition-metal complexes. Part 1. X-Ray crystal and molecular structure of tetrakis[1-o-carboxymethoxyphenoxy)-2-(o-hydroxyphenoxy)ethanato(1–)]dipotassiumcobalt(II), a trinuclear potassium–cobalt–potassium complex

Abstract

The synthesis and X-ray crystal structure of tetrakis[1-(o-carboxymethoxyphenoxy)-2-(o-hydroxyphenoxy)-ethanato(1–)]dipotassiumcobalt(II), [Co(L₂K)₂], a novel neutral K–Co–K complex, is reported. The cobalt(II) ion is tetrahedrally co-ordinated by four carboxyl oxygens, one from each of four open-chain polyether hydroxy-acid anion ligands L^–. The polyether ligands are held in the correct positions to co-ordinate two potassium ions, each potassium being co-ordinated by ten oxygen atoms. Four interligand hydrogen bonds from hydroxy groups to carboxy oxygens add further stability to the [Co(L₂K)₂] structure. Crystals are monoclinic, a= 17.052(4), b= 14.263(4), c= 26.226(6)Å, β= 106.71(2)°, and Z= 4. R= 0.069 for 2 338 reflections.