Co-ordination of alkali metals by open-chain polyethers in transition-metal complexes. Part 3. The X-ray structures of 1-(o-carboxymethoxyphenoxy)-2-(o-hydroxyphenoxy)ethane (HL) and its acid salt, KHL2, a possible intermediate in the formation of Co(KL2)2

Abstract

The X-ray crystal structures of the title compound, HL, and its acid salt, KHL₂, are reported and their hydrogen-bonding schemes compared. HL crystallises in an extended form with intermolecular hydrogen bonding linking the molecules in chains; there are no phenol to carboxyl hydrogen linkages. KHL₂ contains HL₂^– units where the two L ligands are held together by one strong hydrogen bond between the carboxyl groups across a centre of symmetry, and two weaker phenol to carbonyl interactions. The HL₂^– units then form sandwiches round potassium in pentagonal antiprism co-ordination to give a step polymer. The structure of KHL₂ is compared with those of Co(KL₂)₂ and Co(RbL₂)₂, and its role as a possible intermediate in the formation of Co(KL₂)₂ discussed.