Details

Autor(en) / Beteiligte

• Langley, Stuart K
• Wielechowski, Daniel P
• Chilton, Nicholas F
• Moubaraki, Boujemaa
• Murray, Keith S

Titel

A Family of {CrIII 2LnIII 2} Butterfly Complexes: Effect of the Lanthanide Ion on the Single-Molecule Magnet Properties

Ist Teil von

• Inorganic chemistry, 2015-11, Vol.54 (21), p.10497-10503

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2015

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• We report the synthesis of several heterometallic 3d–4f complexes which result from the replacement of the DyIII ions in the [CrIII 2DyIII 2­(OMe)2­(mdea)2­(O2CPh)4­(NO3)2] single-molecule magnet (SMM) by the trivalent Pr, Nd, Gd, Tb, Ho, and Er lanthanide ions. The parent {Cr2DyIII 2} compound displayed an anisotropy barrier to magnetization reversal of 53 cm–1, with magnetic hysteresis observed up to 3.5 K and with large coercive fields at low temperatures (2.7 T at 1.8 K). Magnetic studies for the new complexes revealed significantly different static and dynamic magnetic behavior in comparison to the parent {CrIII 2DyIII 2} complex. When LnIII = Pr, a complete loss of SMM behavior is found, but when LnIII = Nd or Er, frequency-dependent tails in the out-of-phase susceptibility at low temperatures are observed, indicative of slow magnetic relaxation, but with very small anisotropy barriers and fast relaxation times. When LnIII = Tb and Ho, SMM behavior is clearly revealed with anisotropy barriers of 44 and 36 cm–1, respectively. Magnetic hysteresis is also observed up to 2.5 and 1.8 K (0.003 T/s) for the Tb and Ho complexes, respectively. A large loss of the magnetization is, however, observed at zero-field, and as a result, the large coercivity which is present in the {Cr2Dy2} example is lost. The {Cr2Tb2} and {Cr2Ho2} complexes are rare examples of Tb- and Ho-based SMMs which reveal both slow relaxation in the absence of a static dc field (ac susceptibility) and open hysteresis loops above 1.8 K.