A Spectroscopic and Computationally Minimal Approach to the Analysis of Charge-Transfer Processes in Conformationally Fluxional Mixed-Valence and Heterobimetallic Complexes
A Spectroscopic and Computationally Minimal Approach to the Analysis of Charge-Transfer Processes in Conformationally Fluxional Mixed-Valence and Heterobimetallic Complexes
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DOI：
10.1002/chem.201901200
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发表时间：
2019-07-02
影响因子：
4.3
通讯作者：
Low, Paul J.
中科院分区：
文献类型：
--
作者：
Gueckel, Simon;Gluyas, Josef B. G.;Low, Paul J.
II 类混合价双金属配合物{[Cp '(PP)M]C 相当于 C-C 相当于 N[M '(PP)' Cp ']}(2+) (M, M '=Ru, Fe; PP=dppe, (PPh3)(2); Cp '=Cp*, Cp) 在流体溶液中作为构象系综存在，其结构总体范围为 顺式到反式的几何形状。每个构象异构体都会产生自己的一系列低能间隔电荷转移 (IVCT) 和局部 d-d 跃迁，这些跃迁在 NIR 区域重叠，从而在 NIR 吸收光谱中给出复杂的带包络，这阻止了对带形状分析的任何有意义的尝试。然而，在选择对每个配合物的基态势能超曲面进行采样的少量优化结构上，使用色散校正全局混合 (BLYP35-D3) 或局部混合 (lh-SsirPW92-D3) 泛函进行 DFT 和时间相关 (TD)DFT 计算已证明足以解释电子光谱的主要特征。虽然计算费用不大，但与通过使用 Marcus-Hush 理论和导数的静态点电荷模型分析 IVCT 能带，或从单个（全局）最小能量几何进行 TDDFT 计算相比，这种方法可以更准确地描述基础分子电子结构。
Class II mixed-valence bimetallic complexes {[Cp '(PP)M]C equivalent to C-C equivalent to N[M '(PP)' Cp ']}(2+) (M, M '=Ru, Fe; PP=dppe, (PPh3)(2); Cp '=Cp*, Cp) exist as conformational ensembles in fluid solution, with a population of structures ranging from cis- to trans-like geometries. Each conformer gives rise to its own series of low-energy intervalence charge-transfer (IVCT) and local d-d transitions, which overlap in the NIR region, giving complex band envelopes in the NIR absorption spectrum, which prevent any meaningful attempt at analysis of the band shape. However, DFT and time-dependent (TD)DFT calculations with dispersion-corrected global-hybrid (BLYP35-D3) or local hybrid (lh-SsirPW92-D3) functionals on a small number of optimised structures chosen to sample the ground state potential energy hypersurfaces of each of these complexes has proven sufficient to explain the major features of the electronic spectra. Although modest in terms of computational expense, this approach provides a more accurate description of the underlying molecular electronic structure than would be possible through analysis of the IVCT band by using the static point-charge model of Marcus-Hush theory and derivatives, or TDDFT calculations from a single (global) minimum energy geometry.