Coordination Compounds in High-Resolution Nuclear Magnetic Resonance Spectroscopy

Abstract

This review illustrates the broad potential of using nuclear magnetic resonance spectra transformed by complex formation to study the structure and dynamics of heteroatom ligands and their coordination compounds. Such transformations are considered separately for the formation of both paramagnetic and diamagnetic coordination complexes. A section discussing the features of nuclear magnetic resonance in paramagnetic systems precedes the discussion of the molecular structure of specific organic heteroatom compounds and their complexes. These features arise from hyperfine interactions between unpaired electrons localized on the coordinating ion and the resonating nuclei. This results in paramagnetic line broadening and contact and pseudocontact shifts of resonance lines in nuclear magnetic resonance spectra. These paramagnetic shifts and broadenings provide information on molecular structure. The main principles of the paramagnetic additive method are presented; their use enables overcoming difficulties associated with strong paramagnetic broadening of resonance lines in high-resolution nuclear magnetic resonance spectra. It is also shown that the transformation of nuclear magnetic resonance spectra during the formation of diamagnetic coordination compounds yields valuable information on the molecular structure of both ligands and the resulting complexes.