A proton nuclear magnetic resonance investigation of biologically relevant electronic structural and dynamic properties of paramagnetic model compounds for the active sites of hemo-proteins is planned. The use of synthetic prophyrins will permit a quantitative analysis of the paramagnetic shift in terms of the bonding and magnetic properties and will permit a characterization of the metal-porphyrin and metal-axial- ligand bond as a function of metal ion. The nature of the iron- porphyrin and iron-imidazole bonding as a function of iron oxidation state, spin state and stereochemistry will be elucidated as an aid towards understanding the changes in bonding upon oxygenation of hemo- proteins. The influence of systematic, controlled electronic and stereochemical perturbations on the paramagnetic shifts of the model compounds will be quantitatively analyzed in order to form a basis for interpreting the observed shift variations in hemo-proteins in terms of structural and/or electronic effects at the active site. The capability for determining the in-plane magnetic axes and orbital ground states in low-spin ferric and high-spin ferrous porphyrins will be evaluated for a series of model compounds with controlled low-symmetry distortions. The utility of diastereotopic methylene proton splitting as a probe for the extent of metal ion displacement from the heme plane will be assessed. A series of nmr kinetic studies will be initiated to aid in assessing the importance of rate-controlling bond-rupture mechanisms in hemo- proteins, provide estimates of the mobility of out-of-plane metal ions relative to the prophyrin plane by monitoring porphyrin 'inversion', and yield kinetic and mechanistic data on prophyrin electron transfer reactions.