Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, California 94720, USA.
Phys Chem Chem Phys. 2020 Jan 2;22(2):781-798. doi: 10.1039/c9cp04643g.
We report the adiabatic energy decomposition analysis (EDA) of density functional theory (DFT) results, shedding light on the physical content of binding energies and carbon monoxide (CO) frequency (υCO) shifts in select first-row transition metal monocarbonyls (MCOs; M = Ti-, V-, Cr-, Co-, Ni-, Cu-, V, Cr, Mn, Ni, Cu, Zn, Cr+, Mn+, Fe+, Cu+, and Zn+). This approach allows for the direct decomposition of υCO, in contrast to previous studies of these systems. Neutral, anionic, and cationic systems are compared, and our results indicate that the relative importance of electrostatic interactions, intramolecular orbital polarization, and charge transfer can vary significantly with the charge and electron configuration of the metal participating in binding. Various anomalous systems are also discussed and incorporated into a general model of MCO binding. Electrostatic interactions and orbital polarization are found to promote blue shifts in υCO, while charge transfer effects encourage υCO red-shifting; previously reported values of υCO are found to be a result of a complex but quantifiable interplay between these physical components. Our computations indicate that CuCO- and ZnCO possess triplet ground states, and also that CrCO- exhibits a non-linear geometry, all in contrast to previous computational results. Advantages and limitations of this model as an approximation to more complicated systems, like those implicated in heterogeneous catalysis, are discussed. We also report benchmark results for MCO geometries, binding energies, and harmonic CO frequencies, and discuss the validity of single-reference wave function and DFT approaches to the study of these transition metal systems.
我们报告了密度泛函理论（DFT）结果的绝热能量分解分析（EDA），揭示了结合能和一氧化碳（CO）频率（υCO）位移的物理内容，这些内容在选择的第一过渡金属单羰基（MCO；M=Ti-V-Cr-Co-Ni-Cu-V-Cr-Mn-Ni-Cu-Zn、Cr+、Mn+、Fe+、Cu+和 Zn+）中。这种方法允许直接分解 υCO，与以前这些系统的研究不同。我们比较了中性、阴离子和阳离子系统，结果表明，静电相互作用、分子内轨道极化和电荷转移的相对重要性随参与结合的金属的电荷和电子构型而有很大变化。还讨论了各种异常系统，并将其纳入 MCO 结合的一般模型。静电相互作用和轨道极化促进 υCO 蓝移，而电荷转移效应则鼓励 υCO 红移；以前报告的 υCO 值是这些物理成分之间复杂但可量化相互作用的结果。我们的计算表明，CuCO-和 ZnCO 具有三重态基态，而 CrCO-则具有非线性几何形状，这与以前的计算结果相反。讨论了该模型作为更复杂系统（如涉及多相催化的系统）的近似模型的优缺点。我们还报告了 MCO 几何形状、结合能和 CO 谐振动频率的基准结果，并讨论了单参考波函数和 DFT 方法在这些过渡金属系统研究中的有效性。
