Moilanen Jani O, Mansikkamäki Akseli, Lahtinen Manu, Guo Fu-Sheng, Kalenius Elina, Layfield Richard A, Chibotaru Liviu F
University of Jyväskylä, Department of Chemistry, Nanoscience Centre, P.O. Box 35, FI-40014, University of Jyväskylä, Finland.
Dalton Trans. 2017 Oct 10;46(39):13582-13589. doi: 10.1039/c7dt02565c.
The synthesis and structural characterization of two benzoquinone-bridged dinuclear rare-earth complexes [BQ(MCl·THF)] (BQ = 2,5-bisoxide-1,4-benzoquinone; M = Y (1), Dy (2)) are described. Of these reported metal complexes, the dysprosium analogue 2 is the first discrete bridged dinuclear lanthanide complex in which both metal centres reside in pentagonal bipyramidal environments. Interestingly, both complexes undergo significant thermal expansion upon heating from 120 K to 293 K as illustrated by single-crystal X-ray and powder diffraction experiments. AC magnetic susceptibility measurements reveal that 2 does not show the slow relation of magnetization in zero dc field. The absent of single-molecule behaviour in 2 arises from the rotation of the principal magnetic axis as compared to the pseudo-C axis of the pentagonal bipyramidal environment as suggested by ab initio calculations. The cyclic voltammetry and chemical reduction experiments demonstrated that complexes 1 and 2 can be reduced to radical species containing [BQ˙]. This study establishes efficient synthetic strategy to make bridged redox-active multinuclear lanthanide complexes with a pentagonal bipyramidal coordination environment that are potential precursors for single-molecule magnets.
描述了两种苯醌桥联双核稀土配合物[BQ(MCl·THF)]（BQ = 2,5 - 二氧化物 - 1,4 - 苯醌；M = Y (1)，Dy (2)）的合成及结构表征。在这些报道的金属配合物中，镝类似物2是第一个离散的桥联双核镧系配合物，其中两个金属中心都处于五角双锥环境中。有趣的是，如单晶X射线和粉末衍射实验所示，从120 K加热到293 K时，两种配合物都经历了显著的热膨胀。交流磁化率测量表明，2在零直流场中未显示出缓慢的磁化弛豫。从头算计算表明，2中不存在单分子行为是由于主磁轴相对于五角双锥环境的伪C轴发生了旋转。循环伏安法和化学还原实验表明，配合物1和2可以还原为含有[BQ˙]的自由基物种。本研究建立了一种有效的合成策略，用于制备具有五角双锥配位环境的桥联氧化还原活性多核镧系配合物，这些配合物是单分子磁体的潜在前体。
