The application of lanthanides in many fields is closely related to their unusually high coordination number and large charge density. Many uses require complexation of the lanthanide with suitable organic ligands, which then allow, for example, introduction of other functions into systems like chemical nucleases. There are not many structural investigations with such systems. Presently we report here the results for a complex between hydrated lanthanum triflate and [221]cryptand obtained with three independent methods: X-ray diffraction, quantum chemistry calculations and NMR measurements of vicinal spin-spin coupling constants. The complex is of particular interest due to a specific co-ordination sphere with all seven binding sites of the cryptand (five O and both N-atoms) and extra three water molecules grouping from the same side of the compound (through the biggest loop of the cryptand). The analysis of the crystal packing revealed, that in the crystal molecules are assembled into two layers by O-H…O bonds (O…O 2.766(6)-2.867(6)Å) formed by the water molecules and СF3SO3 anions. ECP quantum chemical calculations (Lanl2dz approach) support the structure. Experimental vicinal spin-spin coupling constants between protons of neighboring CH2-groups in solutions (CD3OD and CD3CN) are in a good agreement with the ab’initio calculated ones (PFT DFT with Ub3lyp and 6G/311(d) basis set). So, the specific conformation of the ligand in solutions of the complex and in the solid state is entirely the same.