NMR Spectroscopy—A Versatile Tool for Studying the Structure and Magnetic Properties of Paramagnetic Lanthanide Complexes in Solutions (Review)

Abstract Coordination compounds of lanthanides attract increasing attention of researchers due to their unique physical and chemical properties, including interesting optical and magnetic behavior. Fine tuning of properties of functional materials based on them is possible by controlling the structure of complexes. This review describes the approach of applying NMR spectroscopy to solve the challenging problem of identification of paramagnetic lanthanide complexes, as well as to establish a correlation between the structure of the coordination sphere of lanthanide ions and the magnetic characteristics of the complexes. It has been shown how the analysis of lanthanide-induced shifts (LIS) and lanthanide-induced relaxation (LIR) in series of isostructural compounds contributes to the identification of spectral–structural correlations, which, in combination with X-ray diffraction and quantum-chemical data, make it possible not only to establish the structure of the compound in solution, but also to perform a primary assessment of the possibility of using lanthanides complexes as single molecule magnets.