NMR and Computational Studies of Paramagnetic Compounds

Abstract

Unlike diamagnetic compounds, paramagnetic samples are more difficult to study by NMR because they usually exhibit wide chemical shift ranges and broadened signals. These peculiar features are mainly due to the strong hyperfine interactions between magnetic dipoles of unpaired electrons and nuclei. In order to understand experimentally observed NMR signals from paramagnetic molecules, quantum chemical calculations are often desirable. This thesis focuses on two areas of NMR studies of paramagnetic compounds. First, we have examined solution-state 1H, 13C, and 17O NMR spectra of several small paramagnetic vanadium compounds and established the validity of DFT computational approaches for calculating hyperfine shifts on 1H, 13C, and 17O nuclei. We then attempted to study a protein (transferrin) containing V(III) ions by 17O NMR. Second, we used the solid-state NMR data for paramagnetic Cu(DL-alanine)2•H2O reported in the literature to evaluate a periodic DFT code BAND in computing hyperfine coupling tensors in solids. This is the first time that this kind of test for BAND is carried out for molecular solids.