Analysis of multinuclear lanthanide induced shifts. Part 5. The co-ordination polyhedron of 1 : 3 lanthanide(III)–glycolate complexes in aqueous solution

Abstract

Experimental ¹⁷O, ¹³C, and ¹H bound shifts have been determined for the complexes of lanthanide(III) cations with glycolate (L) in D₂O at pD 4.5. These shifts were separated into diamagnetic, contact, and pseudocontact contributions. The contact shifts show that the stoicheiometry of these complexes is LnL₃(D₂O)₃. Glycolate is co-ordinated in a bidentate fashion via one of the carboxylate oxygens and the hydroxylic oxygen. From the pseudocontact shifts it is concluded that lanthanide(III) cations are surrounded by nine oxygens constituting a distorted tricapped trigonal prism, in which the three capping positions are occupied by carboxylate oxygens.