Auxiliary Rather Than Dominant. The Role of Direct Dy-S Coordination in Single-Molecule Magnet Unveiled via Study.

The role of Dy-S coordination in a single-molecule magnet (SMM) is investigated via an 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 and high effective barrier for magnetic reversal . The best SMMs in the selected group, i.e., (CCDC refcode: PUKFAF) and (CCDC refcode: NIKSEJ), are just those holding the longest τ and the highest simultaneously. Further analysis based on the crystal field model and magneto-structural exploration indicates that the influence of Dy-S coordination on the SMM performance of 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 , 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 and , these new ones are predicted to have significantly longer τ and higher , as well as a nearly doubled blocking temperature . Thus, they are probable candidates of SMM having clearly improved performance.