Synthesis of 3d metallic single-molecule magnets

A methodology for the rigorous nonperturbative derivation of magnetic pseudospin Hamiltonians of mononuclear complexes and fragments based on ab initio calculations of their electronic structure is described. It is supposed that the spin-orbit coupling and other relativistic effects are already taken fully into account at the stage of quantum chemistry calculations of complexes. The methodology is based on the establishment of the correspondence between the ab initio wave functions of the chosen manifold of multielectronic states and the pseudospin eigenfunctions, which allows to define the pseudospin Hamiltonians in the unique way. Working expressions are derived for the pseudospin Zeeman and zero-field splitting Hamiltonian corresponding to arbitrary pseudospins. The proposed calculation methodology, already implemented in the SINGLE_ANISO module of the MOLCAS-7.6 quantum chemistry package, is applied for a first-principles evaluation of pseudospin Hamiltonians of several complexes exhibiting weak, moderate, and very strong spin-orbit coupling effects.

Ab initio calculation of anisotropic magnetic properties of complexes. I. Unique definition of pseudospin Hamiltonians and their derivation.

Magnetic anisotropy in two- to eight-coordinated transition–metal complexes: Recent developments in molecular magnetism

Multi-frequency, high-field EPR as a powerful tool to accurately determine zero-field splitting in high-spin transition metal coordination complexes

Monometallic Ni(II) and Co(II) complexes with large magnetic anisotropy are studied using correlated wave function based ab initio calculations Based on the effective Hamiltonian theory, we propose a scheme to extract both the parameters of the zero-field splitting (ZFS) tensor and the magnetic anisotropy axes Contrarily to the usual theoretical procedure of extraction, the method presented here determines the sign and the magnitude of the ZFS parameters in any circumstances While the energy levels provide enough information to extract the ZFS parameters in Ni(II) complexes, additional information contained in the wave functions must be used to extract the ZFS parameters of Co(II) complexes The effective Hamiltonian procedure also enables us to confirm the validity of the standard model Hamiltonian to produce the magnetic anisotropy of monometallic complexes The calculated ZFS parameters are in good agreement with high-field, high-frequency electron paramagnetic resonance spectroscopy and frequency domain magnetic resonance spectroscopy data A methodological analysis of the results shows that the ligand-to-metal charge transfer configurations must be introduced in the reference space to obtain quantitative agreement with the experimental estimates of the ZFS parameters

Marc Duran

Papers

Very Large Ising‐Type Magnetic Anisotropy in a Mononuclear NiII Complex