The ~(13)C NMR study of the interaction between the trivalent lanthanide ions(from Dy to Lu)and D-pantothenic acid in aqueous solution was presented.The unambiguous resonance assignmentswere made on the basis of pH dependence and the analysis of molecular geometry.~(13)C paramagneticshifts were separated into the contact and dipolar components by Reilley’s method.The complexstability constant is 12.0 L/mol for the 1:1 ytterbium complex.An analysis of the shift data showsthat heavy lanthanide ions form isostructural complexes with the substrate and the hyperfine coupl-ing constant is independent of the ions used in the study.D-pantothenic acid is coordinated to themetal via the two oxygens of the carboxyl group with 2.25 of Ln—O distances.The electron spindensity distribution and the structural details of the complex were elucidated from the shift data.It is stated that contact contributions,while small for nuclei of several bonds away from the metal,should not be dismissed a priori. The ~ (13) C NMR study of the interaction between the trivalent lanthanide ions (from Dy to Lu) and D-pantothenic acid in aqueous solution was presented. The unambiguous resonance assignmentswere made on the basis of pH dependence and the analysis of molecular geometry . (13) C paramagneticshifts were separated into the contact and dipolar components by Reilley’s method. The complexstability constant is 12.0 L / mol for the 1: 1 ytterbium complex. An analysis of the shift data showsthat heavy lanthanide ions form isostructural complexes with the substrate and the hyperfine coupl-ing constant is independent of the ions used in the study. D-pantothenic acid is coordinated to themetal via the two oxygens of the carboxyl group with 2.25 of Ln-O distances.The electron spindensity distribution and the structural details of the complex were elucidated from the shift data. It is stated that contact contributions, while small for nuclei of several bonds away from the metal, should not be dismissed a priori.