Anisotropic Magnetic Spin Interactions
of Transition Metal Complexes
and Metalloenzymes from Spectroscopy
and Quantum Chemistry
Matthias Stein
Abstract Spectroscopic investigations of the interaction of a spin magnetic moment
with an external magnetic field reveal insight into the electronic structure, e.g. the
composition of the occupied molecular orbitals of the system, the oxidation state
of a possible transition metal and its coordination environment. For paramagnetic
systems, electron spin resonance (ESR) and related techniques probe the interaction
between electron and nuclear spins, provide information about the spatial distribution of the spin density and allow identifying binding partners which are often not
resolved structurally, for example hydrogen atoms. In particular, diagonalization of
the electron Zeeman and electron-nuclear hyperfine interaction matrices does not
only give their principal values but also their magnetic principal axes and allows
making statements about the spatial arrangement of coordinating atoms and ligands.
The advancement of computational approaches to calculate the parameters of the
effective Spin Hamiltonian such as the electronic g-tensors and hyperfine tensors
and their comparison with experiment supports the analysis and interpretation of
complex magnetic resonance spectra. This is discussed here for g- and hyperfine
tensors and zero-field splitting tensors for selected examples including transition
metal containing model complexes and metalloenzymes.
1 Introduction
Modern spectroscopic techniques from spin magnetic resonance experiments (either
nuclear spin (NMR) or electron spin (EPR)) are able to give high resolution spectra and very detailed insight into the electronic and coordination structures of small
molecules and proteins. Their analysis and interpretation rely on the concept of an
‘effective Spin Hamiltonian’ that phenomenologically describes the interactions of
the spin (electron or nuclear) with an external magnetic field and introduces specM. Stein (B)
Molecular Simulations and Design Group, Max Planck Institute for Dynamics of Complex
Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany
e-mail: matthias.stein@mpi-magdeburg.mpg.de
© Springer Nature Switzerland AG 2019
E. Broclawik et al. (eds.), Transition Metals in Coordination Environments,
Challenges and Advances in Computational Chemistry and Physics 29,
https://doi.org/10.1007/978-3-030-11714-6_2
35
of Transition Metal Complexes
and Metalloenzymes from Spectroscopy
and Quantum Chemistry
Matthias Stein
Abstract Spectroscopic investigations of the interaction of a spin magnetic moment
with an external magnetic field reveal insight into the electronic structure, e.g. the
composition of the occupied molecular orbitals of the system, the oxidation state
of a possible transition metal and its coordination environment. For paramagnetic
systems, electron spin resonance (ESR) and related techniques probe the interaction
between electron and nuclear spins, provide information about the spatial distribution of the spin density and allow identifying binding partners which are often not
resolved structurally, for example hydrogen atoms. In particular, diagonalization of
the electron Zeeman and electron-nuclear hyperfine interaction matrices does not
only give their principal values but also their magnetic principal axes and allows
making statements about the spatial arrangement of coordinating atoms and ligands.
The advancement of computational approaches to calculate the parameters of the
effective Spin Hamiltonian such as the electronic g-tensors and hyperfine tensors
and their comparison with experiment supports the analysis and interpretation of
complex magnetic resonance spectra. This is discussed here for g- and hyperfine
tensors and zero-field splitting tensors for selected examples including transition
metal containing model complexes and metalloenzymes.
1 Introduction
Modern spectroscopic techniques from spin magnetic resonance experiments (either
nuclear spin (NMR) or electron spin (EPR)) are able to give high resolution spectra and very detailed insight into the electronic and coordination structures of small
molecules and proteins. Their analysis and interpretation rely on the concept of an
‘effective Spin Hamiltonian’ that phenomenologically describes the interactions of
the spin (electron or nuclear) with an external magnetic field and introduces specM. Stein (B)
Molecular Simulations and Design Group, Max Planck Institute for Dynamics of Complex
Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany
e-mail: matthias.stein@mpi-magdeburg.mpg.de
© Springer Nature Switzerland AG 2019
E. Broclawik et al. (eds.), Transition Metals in Coordination Environments,
Challenges and Advances in Computational Chemistry and Physics 29,
https://doi.org/10.1007/978-3-030-11714-6_2
35