Untersuchung der Komplexierung von Na+, K+, Ca2+ und Ba2+ mit einigen elektrisch neutralen Liganden durch Messung von 13C‐chemischen Verschiebungen und Spin‐Gitter‐Relaxationszeiten

Investigation of the complexing of Na+, K+, Ca2+ and Ba2+ with some uncharged ligands by 13C‐chemical shift and spin‐lattice relaxation time measurements The influence of Na+, K+, Ca2+ and Ba2+ ions on 13C chemical shifts and on spin‐lattice relaxation times of some electrically neutral ion carriers was investigated. In the solvents CD3CN and CD3OD 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 CDCl3 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.