Ferrocene Acidity and C–H Bond Dissociation Energy via Experiment and Theory
Ferrocene Acidity and C–H Bond Dissociation Energy via Experiment and Theory
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通过实验和理论研究二茂铁酸度和 C–H 键解离能
DOI：
10.1021/acs.jpca.9b04382
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Kass, Steven R.
中科院分区：
文献类型：
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作者：
Speetzen, Brent;Kass, Steven R.
用傅里叶变换质谱仪测定了二茂铁的气相酸度（ΔH°acid(1) = 391.5±1.3 kcal mol-1）和二茂铁自由基的电子亲和力（EA(1r) = 1.74±0.08 eV），并结合已知的氢原子电离能进行热力学循环，得到了C-H键解离能1（BDE(1) = 118.0±2.3 kcal mol-1）。伴星M06-2X而非B3LYP的计算再现了这些热力学量，并与异常强的芳族C-H BDE相一致。自然种群分析和原子极性张量电荷表明，二茂铁与中性铁原子的共价描述比具有双电荷Fe2+中心的离子描述更能代表该化合物。预测MCp2去质子化后的结构差异，M = Fe和Mg，也符合这一观点。
The gas-phase acidity of ferrocene (ΔH°acid(1) = 391.5 ± 1.3 kcal mol–1) and electron affinity of the ferrocenyl radical (EA(1r) = 1.74 ± 0.08 eV) were measured in a Fourier transform mass spectrometer and combined in a thermodynamic cycle with the known ionization energy of the hydrogen atom to afford the C–H bond dissociation energy of1(BDE(1) = 118.0 ± 2.3 kcal mol–1). Companion M06-2X but not B3LYP computations reproduce each of these thermodynamic quantities and are in accord with an unusually strong aromatic C–H BDE. Natural population analysis and atomic polar tensor charges indicate that a covalent description of ferrocene with a neutral iron atom is a better representation of this compound than an ionic one with a doubly charged Fe2+center. Predicted structural differences upon deprotonation of MCp2, M = Fe and Mg, are also in accord with this view.