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.