直接旋转-旋转合和旋转-翻转刺激对过渡金属复合物的零场分裂的重要性:一个案例研究
1Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerstrasse 12, 53115 Bonn, Germany. theochem@thch.uni-bonn.de
Journal of the American Chemical Society
|August 3, 2006
概括
本研究评估了在过渡金属复合体中零场分裂 (ZFS) 的理论方法,如[Mn(acac) 3]. 直接的旋转-旋转相互作用比以前认为的更为显著,影响了ZFS计算. 先进的初始方法为ZFS提供了更准确的结果.
科学领域:
- 计算化学计算化学
- 量子化学 是一个量子化学.
- 固态物理 固态物理
背景情况:
- 零场分裂 (ZFS) 对于理解过渡金属复合物的磁性质至关重要.
- 准确的理论预测ZFS仍然具有挑战性,特别是关于旋转旋转和旋转轨道合贡献.
- 复杂的[Mn(acac) 3作为评估理论模型的基准.
研究的目的:
- 评估和比较各种理论方法来计算过渡金属复合体中的ZFS.
- 评估对ZFS直接旋转-旋转贡献的意义.
- 调查ZFS计算中不同旋转轨道合 (SOC) 方法的准确性.
主要方法:
- 密度函数理论 (DFT) 具有两个旋转轨道合 (SOC) 的变体.
- 完整的活动空间自相一致场 (CASSCF) 波函数.
- 一开始的方法包括光谱导向配置交互 (SORCI) 和差异专用CI (DDCI).
- 与INDO/S处理进行比较.
主要成果:
- 发现对ZFS的直接旋转-旋转贡献远远大于以前的假设,超过1厘米.
- 两种DFT方法都低估了SOC对ZFS的贡献,至少是两倍.
- 多引用ab initio方法 (SORCI,DDCI) 在[Mn(acac) 3中提供了对ZFS更现实的描述.
- 旋转转刺激是SOC的主要贡献者,即使是在高旋转的d4系统中.
结论:
- 对多重效应的明确处理对于准确的ZFS计算至关重要.
- 最初的方法虽然计算密集,但提供可靠的ZFS预测,并且对中等大小的分子是可行的.
- 这些发现可能适用于广泛的过渡金属复合物.
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