Untersuchung der Komplexierung von Na + , K + , Ca 2+ und Ba 2+ mit einigen elektrisch neutralen Liganden durch Messung von 13 C‐chemischen Verschiebungen und Spin‐Gitter‐Relaxationszeiten

Investigation of the complexing of Na + , K + , Ca 2+ and Ba 2+ with some uncharged ligands by 13 C‐chemical shift and spin‐lattice relaxation time measurements The influence of Na + , K + , Ca 2+ and Ba 2+ ions on 13 C chemical shifts and on spin‐lattice relaxation times of some electrically neutral ion carriers was investigated. In the solvents CD 3 CN and CD 3 OD and in presence of an excess of metal ions ligand 4 (see the Scheme ) forms complexes of 1:1 stoichiometry. All four oxygen atoms of the ligand as well as solvent molecules take part in the coordination. In CDCl 3 as solvent, for all ions investigated except sodium, only 1:2 complexes (metal/ligand) were observed with 4 . Sodium ions form both 1:1 and 1:2 complexes in this solvent. In the 1:2 complexes of the investigated monovalent ions only one, in those of the divalent ions both amide carbonyl groups of ligand 4 take part in the coordination.