Dominance of Cyclobutadienyl Over Cyclopentadienyl in the Crystal Field Splitting in Dysprosium Single-Molecule Magnets.

ABSTRACT: Replacing a monoanionic cyclopentadienyl (Cp) ligand in dysprosium single-molecule magnets (SMMs) with a dianionic cyclobutadienyl (Cb) ligand in the sandwich complexes [(η⁴ -Cb'''')Dy(η⁵ -C₅ Me₄ ^t Bu)(BH₄ )]^- (1), [(η⁴ -Cb'''')Dy(η⁸ -Pn^† )K(THF)] (2) and [(η⁴ -Cb'''')Dy(η⁸ -Pn^† )]^- (3) leads to larger energy barriers to magnetization reversal (Cb''''=C₄ (SiMe₃ )₄ , Pn^† =1,4-di(tri-isopropylsilyl)pentalenyl). Short distances to the Cb'''' ligands and longer distances to the Cp ligands in 1-3 are consistent with the crystal field splitting being dominated by the former. Theoretical analysis shows that the magnetic axes in the ground Kramers doublets of 1-3 are oriented towards the Cb'''' ligands. The theoretical axiality parameter and the relative axiality parameter Z and Z_rel are introduced to facilitate comparisons of the SMM performance of 1-3 with a benchmark SMM. Increases in Z and Z_rel when Cb''' replaces Cp signposts a route to SMMs with properties that could surpass leading systems.

SUBMITTER: Durrant JP 

PROVIDER: S-EPMC9302998 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature