Paramagnetic metal complexes

The hfs (or quadrupole) tensors of geometrically (chemically) equivalent nuclei can be transformed into each other by symmetry operations of the point group of the paramagnetic metal complex. For an arbitrary orientation of B0 these nuclei may be considered as nonequivalent and the ENDOR spectra are described by the simple expressions in (B 4). If B0 is oriented in such a way that the corresponding symmetry group of the spin Hamiltonian is not the trivial one (Q symmetry), symmetry adapted base functions have to be used in the second order treatment for an accurate description of ENDOR spectra. We discuss the C2v and D4h covering symmetry in more detail. 

Lauffer RB (1987) Paramagnetic metal complexes as water proton relaxation agents for NMR imaging theory and design. Chem. Rev. 87 901-927. 

The lowest excited states of paramagnetic metal complexes are described by configuration interactions of the porphyrin (7T,tt ) excited singlet and triplet states and the "porphyrin-to-metal" or metal-to-porphyrin charge-transfer excited states (35,36). Thus T (phosphorescence) emission of paramagnetic metal complexes decays... 

A third possible way to carry out the addition of oxygen to C = C bonds involves paramagnetic metal complexes in which the unpaired electron resides... 

This contribution to the shift is quite difficult to evaluate, because in general the spin density distribution all over the space is not known. The approach to this problem should be stepwise. We first consider that the unpaired electron is localized on the metal nucleus in a paramagnetic metal complex. We refer to this as to the metal-centered point-dipole approximation. Surely this contribution will always be present and often dominant. Then we will discuss the consequences of relaxing this condition. Even in the metal-centered approximation several cases should be discussed. 

NMR provides a powerful tool for the investigation of paramagnetic metal complexes paramagnetism allows the resolution of magnetically non equivalent environments that cannot be resolved in a comparable diamagnetic system. Furthermore the large expansion of the chemical shift range of the observed resonances (the isotropic shift) permits the characterization of fast dynamic processes. 

Jerzykiewicz, M., Drozd, J., and Jezierski, A. (1999). Organic radicals and paramagnetic metal complexes in municipal solid waste composts. An EPR and chemical study. Chemosphere 39, 253-268. 

Paramagnetic Metal Complexes Valence Tautomerism and Persistent Radical... 

Paramagnetic metal complexes with heterocyclic nitroxyl radicals as ligands 89MI2. 

The extent to which a contrast agent acts to effect MRI enhancement, termed relaxivity [6-8,10,11], is highly dependent on the magnitude of the dipole-dipole interactions between the electron spin on a paramagnetic metal complex and the proton spin on the water molecule in question. The development of an effective MRI... 

Paramagnetic metal complexes have been doped into Uquid crystals to achieve easier alignment. The critical magnetic field required for reorientation of 5CB doped with the iron(III) complex 5,10,15,20-tetraphenylporphyrinatoiron(III) chloride, FeTPPCl, was found to be one fourth of that needed for alignment of pure The concentra-... 

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