TY - JOUR
T1 - Structural tailoring effects on the magnetic behavior of symmetric and asymmetric cubane-type Ni complexes
AU - Ponomaryov, Alexey N.
AU - Kim, Namseok
AU - Hwang, Jaewon
AU - Nojiri, Hiroyuki
AU - Van Tol, Johan
AU - Ozarowski, Andrew
AU - Park, Jena
AU - Jang, Zeehoon
AU - Suh, Byoungjin
AU - Yoon, Sungho
AU - Choi, Kwang Yong
PY - 2013/6
Y1 - 2013/6
N2 - Using two kinds of carboxylate ligands with small but significant differences in steric size, symmetric and asymmetric FeII and Ni II cubanes have been synthesized in a controlled fashion. Fast sweeping pulsed field measurements showed magnetization hysteresis loops for two cubane-type molecular complexes, [Ni4(μ-OMe)4(O 2CAr4F-Ph)4(HOMe)8] and [Ni 4(μ-OMe)4(O2CArTol) 4(HOMe)6], thus suggesting single-molecule magnet behavior. To differentiate the magnetic properties between the symmetric and asymmetric cubanes, detailed electron paramagnetic resonance (EPR) measurements were performed. From the EPR data, taken at various frequencies and temperatures, zero-field splitting parameters D, E, and other higher-order parameters for both cubane samples were extracted. Compared to the symmetric N-cubane, the asymmetric one shows an increase in the D and E values by about 20 %, thereby suggesting structural engineering effects on the magnetic properties. By using the magnetic parameters determined by EPR, a static magnetization curve at 2 K and a temperature dependence of the magnetic susceptibility were simulated. A good agreement between theoretical and experimental data confirms the validity of the values obtained from EPR measurements.
AB - Using two kinds of carboxylate ligands with small but significant differences in steric size, symmetric and asymmetric FeII and Ni II cubanes have been synthesized in a controlled fashion. Fast sweeping pulsed field measurements showed magnetization hysteresis loops for two cubane-type molecular complexes, [Ni4(μ-OMe)4(O 2CAr4F-Ph)4(HOMe)8] and [Ni 4(μ-OMe)4(O2CArTol) 4(HOMe)6], thus suggesting single-molecule magnet behavior. To differentiate the magnetic properties between the symmetric and asymmetric cubanes, detailed electron paramagnetic resonance (EPR) measurements were performed. From the EPR data, taken at various frequencies and temperatures, zero-field splitting parameters D, E, and other higher-order parameters for both cubane samples were extracted. Compared to the symmetric N-cubane, the asymmetric one shows an increase in the D and E values by about 20 %, thereby suggesting structural engineering effects on the magnetic properties. By using the magnetic parameters determined by EPR, a static magnetization curve at 2 K and a temperature dependence of the magnetic susceptibility were simulated. A good agreement between theoretical and experimental data confirms the validity of the values obtained from EPR measurements.
KW - EPR spectroscopy
KW - N-cubanes
KW - carboxylate ligands
KW - magnetic properties
KW - steric hindrance
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U2 - 10.1002/asia.201300054
DO - 10.1002/asia.201300054
M3 - Article
C2 - 23509044
AN - SCOPUS:84878320156
VL - 8
SP - 1152
EP - 1159
JO - Chemistry - An Asian Journal
JF - Chemistry - An Asian Journal
SN - 1861-4728
IS - 6
ER -