Chelating Guanidinates for Dysprosium(III) Single‐Molecule Magnets†

Main observation and conclusion Two chelating guanidinate‐based dysprosium(III) complexes, namely the monomeric {(Me 3 Si) 2 NC(N i Pr) 2 } 2 Dy( μ ‐Cl) 2 Li(THF) 2 1 and the dimeric [{(Me 3 Si) 2 NC(N i Pr) 2 } 2 Dy( μ ‐Cl)] 2 2, have been confirmed to be single‐molecule magnets. Moreover, the alteration from 1 to 2 leads to an obvious mitigated quantum tunnelling of magnetization at zero field of the hysteresis loop and much enhanced magnetic relaxation barrier (up to 312 K). 5% dilution with the yttrium(III) analogue for 2 shows no clear change for the hysteresis, indicating the single‐ion nature of the magnetic behavior.