Wada Hisami, Ooka Sayaka, Yamamura Tomoo, Kajiwara Takashi
Department of Chemistry, Faculty of Science, Nara Women's University , Nara 630-8506, Japan.
Institute for Materials Research, Tohoku University , Aoba-ku, Sendai 980-8577, Japan.
Inorg Chem. 2017 Jan 3;56(1):147-155. doi: 10.1021/acs.inorgchem.6b01764. Epub 2016 Dec 12.
Two sets of isostructural Ln(III) mononuclear complexes, [Ln(NO)(18-crown-6)] (Ln = Ce (1), Pr (2), and Nd (3)) and [Ln(NO)(1,10-diaza-18-crown-6)] (Ln = Ce (4), Pr (5), and Nd (6)), were synthesized, and their slow magnetic relaxation behavior was investigated. Since Ln(III) ions are located in an axially stressed ligand field in both sets of complexes, they can exhibit single-molecule magnet (SMM) behavior owing to the oblate-type electronic distributions of the ground sublevels found in Ce(III), Pr(III), and Nd(III). Field-induced slow magnetic relaxation was observed for Ce(III) and Nd(III) complexes 1, 3, 4, and 6 under an applied bias dc field of 1000 Oe, whereas no slow relaxation was observed for Pr(III) complexes 2 and 5. The slow magnetic relaxation behavior of 1, 3, 4, and 6 was correlated with the even-numbered J sublevels of Ce(III) and Nd(III) ions, known as the Kramers system.
合成了两组同构的Ln(III)单核配合物，[Ln(NO)(18-冠-6)]（Ln = Ce (1)、Pr (2) 和Nd (3)）以及[Ln(NO)(1,10-二氮杂-18-冠-6)]（Ln = Ce (4)、Pr (5) 和Nd (6)），并研究了它们的慢磁弛豫行为。由于两组配合物中Ln(III)离子都处于轴向应力配体场中，由于在Ce(III)、Pr(III)和Nd(III)中发现的基态子能级的扁球形电子分布，它们可以表现出单分子磁体（SMM）行为。在1000 Oe的外加偏置直流场下，观察到Ce(III)和Nd(III)配合物1、3、4和6的场诱导慢磁弛豫，而Pr(III)配合物2和5未观察到慢弛豫。1、3、4和6的慢磁弛豫行为与Ce(III)和Nd(III)离子的偶数J子能级相关，即所谓的克莱默斯体系。
