Variational Energy Decomposition Analysis of Charge-Transfer Interactions between Metals and Ligands in Carbonyl Complexes,Inorganic Chemistry

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Variational Energy Decomposition Analysis of Charge-Transfer Interactions between Metals and Ligands in Carbonyl Complexes
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2021-08-30 , DOI: 10.1021/acs.inorgchem.1c01367
Jingting Han ₁ , Adam Grofe _{1,

2} , Jiali Gao _{2,

3,

4}

Affiliation

Variational energy decomposition analyses have been presented to quantify the σ-dative, ligand-to-metal forward charge transfer (CT) and the π-conjugative, metal-to-ligand backward charge delocalization on a series of isolelectronic transition-metal carbonyl complexes M(CO)₆, including M = Ti^2–, V^–, Cr, Mn⁺, and Fe²⁺. Although the qualitative features of these energy terms are understood, well-defined quantitative studies have been scarce. Consistent with early findings, electrostatic and Pauli exchange effects play a key role in σ-donation, resulting in blue shifts in ligand vibrational frequency in the complex geometries. Excluding chemical bonding interactions between the CO ligand and the metal fragments in the energy decomposition analysis, we found that loosely bound electrostatic complexes can be formed at a longer metal-to-ligand distance due to the exponential decay of Pauli exchange. In all complexes, the overall binding stabilization can be attributed to CT effects, with opposing trends between σ-donation and π-back bonding that follows an order of Ti^2– (4.4) > V^1– (2.6) > Cr (1.5) > Mn¹⁺ (1.1) > Fe²⁺ (0.5) in π-to-σ CT ratio. These electronic and energetic features are mirrored in the vibrational frequency shifts induced by different factors. The present investigation may help stimulate the use of energy decomposition techniques to understand the structure and activity of metallocatalysts using density functional theory.

中文翻译：

羰基配合物中金属与配体间电荷转移相互作用的变分能量分解分析

已经提出了变分能量分解分析来量化一系列等电子过渡金属羰基配合物 M 上的 σ 配体、配体到金属的正向电荷转移 (CT) 和 π 共轭、金属到配体的反向电荷离域化(CO) ₆，包括M = Ti ^2–、V ^–、Cr、Mn ⁺和Fe ²⁺. 尽管这些能量术语的定性特征已被理解，但定义明确的定量研究却很少。与早期的发现一致，静电和泡利交换效应在 σ-捐赠中起着关键作用，导致复杂几何结构中配体振动频率的蓝移。在能量分解分析中排除 CO 配体和金属碎片之间的化学键相互作用，我们发现由于泡利交换的指数衰减，可以在更长的金属-配体距离处形成松散结合的静电配合物。在所有配合物中，整体结合稳定性可归因于 CT 效应，σ-捐赠和 π-背键之间的相反趋势遵循 Ti ^2– (4.4) > V ^1–(2.6) > Cr (1.5) > Mn ¹⁺ (1.1) > Fe ²⁺ (0.5) π-σ CT 比。这些电子和能量特征反映在由不同因素引起的振动频移中。目前的研究可能有助于促进能量分解技术的使用，以使用密度泛函理论了解金属催化剂的结构和活性。

更新日期：2021-09-20

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