Auxiliary Rather Than Dominant. The Role of Direct Dy–S Coordination in Single-Molecule Magnet Unveiled via <i>ab initio</i> Study
Yufei Wang, Yuxi Wang, Qi-Qi Yang, Bing Yin
Abstract
The role of Dy–S coordination in a single-molecule magnet (SMM) is investigated via an ab initio study in a group of mononuclear structures. The SMM performance of this group is well interpreted via a concise criterion consisting of long quantum tunneling of magnetization (QTM) time τ QTM and high effective barrier for magnetic reversal U eff . The best SMMs in the selected group, i.e., 1Dy (CCDC refcode: PUKFAF) and 2Dy (CCDC refcode: NIKSEJ), are just those holding the longest τ QTM and the highest U eff simultaneously. Further analysis based on the crystal field model and ab initio magneto-structural exploration indicates that the influence of Dy–S coordination on the SMM performance of 1Dy is weaker than that of axial Dy–O coordination. Thus, Dy–S coordination is more likely to play an auxiliary role rather than a dominant one. However, if placed at the suitable equatorial position, Dy–S coordination could provide important support for good SMM performance. Consequently, starting from 1Dy, we built two new structures where Dy–S coordination only exists at the equatorial position and two axial positions are occupied by strong Dy–O/Dy–F coordination. Compared to 1Dy and 2Dy, these new ones are predicted to have significantly longer τ QTM and higher U eff, as well as a nearly doubled blocking temperature T B . Thus, they are probable candidates of SMM having clearly improved performance.