Reliable Quantum Chemical Prediction of the Localized/Delocalized Character of Organic Mixed-Valence Radical Anions. From Continuum Solvent Models to Direct-COSMO-RS
Reliable Quantum Chemical Prediction of the Localized/Delocalized Character of Organic Mixed-Valence Radical Anions. From Continuum Solvent Models to Direct-COSMO-RS
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DOI：
10.1021/ct300545x
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发表时间：
2012-11-01
影响因子：
5.5
通讯作者：
Kaupp, Martin
中科院分区：
文献类型：
--
作者：
Renz, Manuel;Kess, Martin;Kaupp, Martin
最近提出的一个量子化学协议的有机混合价（MV）化合物的字符的描述，从双方的本地化/离域的边界线，评估和扩展一系列的二硝基芳基自由基阴离子1-6。全局混合泛函与35%（BLYP 35）或42%（BMK）的精确交换混合物与适当的溶剂建模的组合允许基本上定量的处理，例如，在罗宾/戴II类系统，热电子转移（ET）障碍，和价间电荷转移（IV-CT）激发能的结构对称性破缺，同时也涵盖了离域III类的情况。具有较低精确交换混合物的全局混合泛函（例如，B3 LYP、M05或M06）提供了过于离域的描述，而具有更高精确交换混合物（M05-2X、M06-2X）的泛函提供了过于局部化的描述。B2 PLYP双杂化给出了合理的结构，但在II类情况下势垒太小。CAM-B3 LYP范围混合物给出了有点太高的ET势垒和IV-CT能量，而范围混合物omega B 97 X和LC-BLYP明显表现出太多的精确交换。连续溶剂模型描述的情况，以及在大多数非质子溶剂的研究。1，4-二硝基苯阴离子1从质子惰性溶剂中的III类行为转变为醇类中的II类行为不能用连续溶剂模型恢复。与此相反，它是忠实地处理的新的直接导体般的筛选模型的真实的溶剂（D-COSMO-RS）。的D-COSMO-RS方法，TURBOMOLE实施的报告，也准确地描述了增加的ET屏障的II类系统2和3的醇相比，非质子溶剂，可以区分至少定性不同的非质子溶剂具有相同或相似的介电常数。这些MV自由基阴离子的ET字符的溶剂环境的主导作用被强调，相反，在一些以前的计算建议基本上所有的本系统具有离域III类字符在气相中。本方法允许从气相到非质子和质子溶剂环境的准确估计，而不需要明确的从头算分子动力学模拟，并且没有人为的约束。
A recently proposed quantum-chemical protocol for the description of the character of organic mixed-valence (MV) compounds, close from both sides to the localized/delocalized borderline, is evaluated and extended for a series of dinitroaryl radical anions 1-6. A combination of global hybrid functionals with exact-exchange admixtures of 35% (BLYP35) or 42% (BMK) with appropriate solvent modeling allows an essentially quantitative treatment of, for example, structural symmetry breaking in Robin/Day class II systems, thermal electron transfer (ET) barriers, and intervalence charge transfer (IV-CT) excitation energies, while covering also the delocalized class III cases. Global hybrid functionals with lower exact exchange admixtures (e.g., B3LYP, M05, or M06) provide a too delocalized description, while functionals with higher exact exchange admixtures (M05-2X, M06-2X) provide a too localized one The B2PLYP double hybrid gives reasonable structures but far too small barriers in class II cases. The CAM-B3LYP range hybrid gives somewhat too high ET barriers and IV-CT energies, while the range hybrids omega B97X and LC-BLYP clearly exhibit too much exact exchange. Continuum solvent models describe the situation well in most aprotic solvents studied. The transition of 1,4-dinitrobenzene anion 1 from a class HI behavior in aprotic solvents to a class II behavior in alcohols is not recovered by continuum solvent models. In contrast, it is treated faithfully by the novel direct conductor-like screening model for real solvents (D-COSMO-RS). The D-COSMO-RS approach, the TURBOMOLE implementation of which is reported, also describes accurately the increased ET barriers of class II systems 2 and 3 in alcohols as compared to aprotic solvents and can distinguish at least qualitatively between different aprotic solvents with identical or similar dielectric constants. The dominant role of the solvent environment for the ET character of these MV radical anions is emphasized, as in contrast to some previous computational suggestions essentially all of the present systems have delocalized class III character in the gas phase. The present approach allows accurate estimates from the gas phase to aprotic and protic solvent environments, without the need for explicit ab initio molecular dynamics simulations, and without artificial constraints.