由于3d单金属配合物的合成可及性和相对的结构简单性,可以通过几何控制来调节其磁性。单齿配体为微调配位环境提供了巨大的潜力,可用于设计轴向和菱形零场分裂(ZFS)参数。在[CoCl 3(DABCO)(HDABCO)](1)中,三角双锥体Co(II)中心具有两个庞大的轴向配体和三个赤道氯化物配体。对1的深入实验和理论研究表明,由于C施加了严格的轴向对称性,因此大的易平面磁各向异性(+ ve D)具有可忽略的菱形零场分裂(E)3个对称配体和三角空间群。使用高场EPR和频域磁共振(FDMR)研究直接推断出大的易平面磁各向异性( D = +44.5 cm -1)。从头算计算表明,在约4085 cm -1处, 4 E′态的基态/激发态混合对D项有很大的正贡献,而自旋-跃迁跃迁也有较小的贡献。1中缓慢放松的性质通过分析磁化弛豫速率,并考虑了拉曼和直接自旋-晶格弛豫过程以及磁化的量子隧穿(QTM),来阐明这一点。基于τ在2
Effects of<i>d</i>-orbital occupancy on the geometry of the trigonal–bipyramidal complexes [<i>M</i><sup>II</sup>Cl<sub>3</sub>(Hdabco)(dabco)]<sub><i>n</i></sub>, where<i>M</i>is Mn, Co, Ni or Cu and dabco is 1,4-diazabicyclo[2.2.2]octane
作者:Robin G. Pritchard、Majid Ali、Abdul Munim、Asma Uddin
DOI:10.1107/s0108270106037504
日期:2006.11.15
Geometric data from (1- aza- 4- azoniabicyclo[ 2.2.2] octane-kappa N-1)( 1,4- diazabicyclo[ 2.2.2] octane-kappa N-1) trichloromanganese(II), [MnCl3( C6H13N2)(C6H12N2)] or [ MnCl3( Hdabco)( dabco)] ( dabco is 1,4- diazabicyclo[ 2.2.2] octane), and the cobalt( II) analogue, [CoCl3(C6H13N2)(C6H12N2)], have been combined with previously reported data for the Ni and Cu analogues to show that bond-length trends across the isotypal series are consistent with a high-spin trigonal-bipyramidal system. As each transition metal is positioned on a D-3 site in the space group R32 ( No. 155), two bond lengths fully de ne each trigonal-bipyramidal coordination geometry [ Mn-Cl = 2.3903 ( 7) angstrom and Mn-N = 2.367 ( 2) angstrom, and Co - Cl = 2.3080 (8) angstrom and Co-N = 2.269 (3) angstrom].