Premium
Magnetic Resonance of Paramagnetic Complexes
Author(s) -
Keller Heimo J.,
Schwarzhans Karl E.
Publication year - 1970
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.197001961
Subject(s) - unpaired electron , electron paramagnetic resonance , paramagnetism , spectral line , chemistry , relaxation (psychology) , nmr spectra database , transition metal , spin–lattice relaxation , nuclear magnetic resonance , condensed matter physics , physics , psychology , social psychology , biochemistry , astronomy , catalysis
The line width of the ESR and NMR signals of paramagnetic transition metal complexes is determined mainly by the electron spin‐lattice relaxation time τ e . Values of τ e greater than 10 −9 lead to ESR spectra that are readily resolved, while values smaller than 10 −11 give NMR spectra having small line widths. Since fast relaxation processes are effective in nearly all transition metal complexes with several unpaired electrons and in all complexes having an orbitally degenerate ground state, the NMR method has a wider scope. The sign and magnitude of the electron‐nucleus coupling can be determined with great sensitivity from the NMR spectra, whereas only the magnitude of this interaction can be determined from the ESR spectra. Free spin densities can be found very accurately from the NMR shifts, and the method can therefore be advantageously applied to kinetic measurements, e.g. on short‐lived contact complexes.