杜瓦尔二烯基基离子及其环开放反应
Thomas Bally1, Stephan Matzinger, Pawel Bednarek
1Department of Chemistry, University of Fribourg, Switzerland. Thomas.Bally@unifr.ch
Journal of the American Chemical Society
|June 15, 2006
概括
使用光学光谱学观察了Dewar (1*+) 的基离子. 它的电荷共振带表明奇数电子位于pi分子轨道中,表明在77 K处的稳定结构.
科学领域:
- 物理化学 物理化学
- 频谱学是一种光谱学.
- 计算化学计算化学
背景情况:
- 基离子是化学反应中至关重要的反应性中间体.
- 德华是一种具有独特电子性质的的应变异构体.
- 了解基离子的稳定性和反应性,可以了解反应机制.
研究的目的:
- 通过光学光谱学生成和描述Dewar (1*+) 的基离子.
- 在冷矩阵中研究1*+的电子结构和稳定性.
- 阐明了1*+分解为二 (2*+) 的基离子的反应机制.
主要方法:
- 在低温矩阵中生成和观察Dewar二烯 (1*+) 的基离子.
- 光学光谱学用于识别特征性电荷共振波段.
- 理论计算包括TD-DFT和CASPT2来预测过渡能量和几何.
- 分析潜在能量表面和反应路径,包括避免交叉.
主要成果:
- 杜瓦尔 (1*+) 的基离子被成功生成和观察.
- 确定了600nm的电荷共振带,类似于norbornadiene基离子,表明奇数电子的pi-MO定位.
- 理论方法 (TD-DFT,CASPT2) 低估了电荷共振过渡能量,暗示了几何差异.
- 至少7-8kcal/mol的动力屏障将1*+与其衰变产物2*+分开,使得在77K的温度下进行观测.
- 1*+到2*+的环开放是通过一个多步骤的过程进行的,涉及两个避免的交叉和伪辩论过渡.
结论:
- 德华 (1*+) 的基离子在低温矩阵中具有稳定的结构,这是由于显著的动力屏障.
- 电子结构的特点是奇数电子位于pi分子轨道中.
- (2*+) 基离子的衰变机制涉及电子状态之间的复杂的表面跳跃.
相关概念视频
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