Abstract
Ab initio CASSCF calculations have been undertaken to probe the origin of magnetic anisotropy in two structurally related {DyIIIN8} SIMs {[Dy(tmtaa)2]– and [K(DME)2][Dy(tmtaa)2]; 1 and 2, respectively}. Our calculations reveal that complex 1 possesses a larger barrier for reorientation of magnetization (Ucal) than does 2. This is essentially due to the intrusion of K+ ions, which distort the geometry and the donor abilities of the ligands in complex 2, compared with 1. Moreover, the ligand field around DyIII was found to stabilize |mJ> = |±13/2> as the ground state, with stronger mixing by other |mJ> levels. This corresponds to the observation of large gxx and gyy values at the ground state, leading to an efficient QTM process and very fast relaxation. The computed ground‐state |mJ> levels and the estimated g tensors for both complexes are in agreement with experimental results obtained from magnetic and EPR spectroscopic studies. In addition, we have developed various magneto–structural correlations for complexes 1 and 2, in order to understand how small structural distortions are likely to influence the magnetic anisotropy. These correlations offer clues to enhancing the barrier height for magnetization reversal in {DyIIIN8} complexes.
Published Version
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