In the last decade, there has been an exponential growth of molecular magnets based on the lanthanide ions . Lanthanide ions are at the core of the most promising magnetic materials such as single molecule magnets, single chain magnets, room temperature ferromagnets and photo-switchable magnets. The growing amount of detailed experimental data requires the high-level quantum chemical calculations to describe the electronic and magnetic properties of lanthanide compounds. The CASSCF/SO-RASSI approach based on the relativistic Douglas-Kroll-Hess Hamiltonian with non-perturbative account for the spin-orbit coupling (SOC) was demonstrated to perform well to reproduce anisotropic magnetic properties of mononuclear lanthanide complexes .
Recently , we performed first ab-initio calculations of the spectroscopic and magnetic properties of more complicated systems, namely, decamethyllanthanocene compexes with paramagnetic ligand (radical-anion of substituted sulfur diimin). Results of our calculations demonstrated unexpectedly strong exchange interaction (both isotropic and asymmetric) in the case of ytterbocene complex. Earlier [3,4], R. Andersenís group performed thorough and comprehensive experimental study of the similar ytterbocene and decamethylytterbocene compexes with bipyridine and a series of its derivatives.
The report will present and discuss results of the CASSCF/CASPT2/SO-RASSI calculations for the ytterbocene complexes with sulfur diimide and bipyridine ligands. The temperature dependences of magnetic susceptibility and other properties calculated from a first principle will be compared with experiment and interpreted using parameters of pseudospin Hamiltonian also evaluated using results of ab initio calculations.
This work was supported by the Russian Science Foundation (project 16-13-10155).
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3. C.H. Booth, D. Kazhdan, E.L Werkema et al. J. Am. Chem. Soc. 2009, 131, 6481.
4. C.H. Booth, M.D. Walter, D. Kazhdan et al. J. Am. Chem. Soc. 2010, 132, 17537.