在 bis () (II) 复合体中,由于硬质强制的连接体旋转而导致的旋转状态的改变
Erik D Brady1, Jason S Overby, M Brett Meredith
1Contribution from the Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA.
Journal of the American Chemical Society
|August 9, 2002
概括
在有机 (II) 双 (II) 烯复合体中的绝缘散体改变了连接体的方向,改变了磁性特性. 这种自旋状态操纵提供了一条通往磁性调节分子的途径.
科学领域:
- 有机金属化学 有机金属化学
- 无机化学 无机化学
- 材料科学 材料科学 材料科学
背景情况:
- 环乙环通常不会影响过渡金属复合体中的d轨道能量.
- 碳循环连接物,与环丁不同,可以根据它们的对齐来改变磁性.
- 替代的有机 (II) 双 (II) () 综合体为研究这些效应提供了一个模型系统.
研究的目的:
- 研究印尼基联体的旋转方向如何影响有机 (II) 复合物的磁性.
- 探索替代剂对控制连接体构成和旋转状态的固体阻碍的作用.
- 为了确定连接体的方向是否可以用来调整金属复合物的磁性行为.
主要方法:
- 合成单替代和非替代的有机 (II) 双 (II) ) 复合物,使用替代的 (II) 和 (II) 化物.
- 测量磁敏度以确定旋转状态 (高旋转与低旋转).
- 进行X射线衍射分析以阐明结构构造 (分层与左侧) 和键距离.
- 计算建模以了解连接体定向对金属d轨道和HOMO-LUMO间隙的电子效应.
主要成果:
- 单替代复合物 ((1-RC(9) H(6)) ((2) Cr) 是高旋转的 (S=4),采用一个分阶段的内基构造.
- 具有庞大的t-Bu或SiMe群的异位复合体 ((1,3-R(2) C(9) H(5)) ((2) Cr) 是低旋转的 (S=2),采用了固态强加的左边形状.
- X射线衍射证实了单置换复合体中的分级构造和非置换复合体中的左构造,后者具有较短的Cr-C键长度.
- 计算显示,左边形状增加了金属联体轨道混合,增加了HOMO-LUMO间隙,并有利于低旋转状态.
结论:
- 印尼联体上的硬质体质量有效地控制了它们的旋转方向,决定了有机 (II) 复合物的旋转状态.
- 从分层到左边的内导向的变化对电子结构和磁性特性产生了重大影响.
- 立体强加的连接体旋转为设计和合成具有可调节磁性特征的分子提供了一个可行的策略.
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