为什么 (SiO) ((4) 被计算为四面体,而 (CO) ((4) 是正方形平面? 一个分子轨道分析
Sebastian Kozuch1, David A Hrovat, Weston Thatcher Borden
1Department of Chemistry and Center for Advanced Scientific Computing and Modeling (CASCaM), University of North Texas , Denton, TX 76201, United States.
Journal of the American Chemical Society
|December 17, 2013
概括
像 (SiO) 4和 (SiS) 4这样的四环丁化合物喜欢三重基态的四面体结构,与它们的碳同类不同. 这种几何偏好受到电子阴性差异的影响,正如 Jahn-Teller 效应所解释的那样.
科学领域:
- 计算化学计算化学
- 量子化学 是一个量子化学.
- 材料科学 材料科学 材料科学
背景情况:
- 分子轨道 (MO) 理论为分子的电子结构和稳定性提供了洞察力.
- 了解新型无机化合物的基本状态和几何结构对于预测它们的性质至关重要.
研究的目的:
- 为了研究正方形平面四环丁化合物的基本状态和平衡几何,特别是 (SiO) 4和 (SiS) 4.
- 为了比较这些基于的化合物的电子和结构性质与它们的碳类似物, (CO) 4和 (CS) 4.4.
- 为了合理化观察到的几何偏好,使用理论原理,如第二阶的Jahn-Teller效应.
主要方法:
- 使用了高层次的初始计算,包括 (U)CCSD(T) -F12b/cc-pVTZ-F12//(U) B3LYP/6-311+G(2df).
- 密度函数理论 (DFT) 用于几何优化.
- 定性分子轨道 (MO) 理论和二阶恩-泰勒效应被用于理论分析.
主要成果:
- 计算证实,正方形平面D4h-(SiO) 4和D4h-(SiS) 4具有三重基本状态.
- 与它们的碳对应物相反, (SiO) 4和 (SiS) 4表现出具有四面体 (Td) 均衡几何和缺电子Si-Si键的低能单体状态.
- (CO) 4和 (CS) 4在它们的最低单元状态中,更喜欢D4h几何而不是Td几何.
- 对二次恩-泰勒效应的分析成功合理化了基于电子阴性差异的几何偏好.
结论:
- 由于电子因素,四环丁化合物 (SiO) 4和 (SiS) 4有利于四面体几何形状,与平面碳类似物形成鲜明对比.
- 构成原子之间的电子阴性差异在确定 (AY) 4 系统的平衡几何学方面发挥着重要作用.
- 对于 (BF) 4和 (BCl) 4的理论预测,与 (CO) 4和 (CS) 4的同电子,建议偏好Td几何形状,与 (BCl) 4实验证实.
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