Steady-State Spectroscopic Analysis of Proton-Dependent Electron Transfer on Pyrazine-Appended Metal Dithiolenes [Ni(pdt)2], [Pd(pdt)2], and [Pt(pdt)2] (pdt = 2,3-Pyrazinedithiol).
Steady-State Spectroscopic Analysis of Proton-Dependent Electron Transfer on Pyrazine-Appended Metal Dithiolenes [Ni(pdt)2], [Pd(pdt)2], and [Pt(pdt)2] (pdt = 2,3-Pyrazinedithiol).
复制标题
吡嗪金属二硫烯 [Ni(pdt)2]、[Pd(pdt)2] 和 [Pt(pdt)2] 上质子依赖性电子转移的稳态光谱分析（pdt = 2,3-吡嗪二硫醇）
作者：
Steven R. Kennedy;Morgan N Kozar;H. Yennawar;B. J. Lear
我们报道了一系列ML 2金属二硫杂环戊烯配合物的结构、电子和酸碱性质，其中M = Ni，Pd，Pt，L = 2，3-吡嗪二硫醇.这些配合物是非无辜的，并且在金属中心的配体之间具有强的电子耦合。电子耦合可以很容易地量化在单阴离子的混合价态，使用马库斯-Hush理论。价间电荷转移（IVCT）带的分析表明，Ni、Pd和Pt配合物在混合价态的电子耦合分别为5800、4500和5700 cm（-1）。然后，我们专注于他们的反应，酸滴定的混合价态，产生不对称质子化的混合价混合质子化状态。对于所有三个复合物，质子化的结果在严重的衰减的电子耦合，测量的IVCT带。我们发现Ni和Pt的电子耦合降低了近5倍，而对于Pd配合物，电子耦合降低到不再观察到IVCT带的程度。我们把电子耦合的减少归因于不对称质子化引起的电荷钉扎。更严重的减少耦合的Pd络合物是更大的配体和金属轨道之间的能量失配的结果，反映在较小的电子耦合的纯混合价态。这项工作表明，桥接金属中心可以用来调整混合价和混合价混合质子化状态的电子耦合，以及伴随质子化状态变化的电子耦合的变化幅度。
We report the structural, electronic, and acid/base properties of a series of ML2 metal dithiolene complexes, where M = Ni, Pd, Pt and L = 2,3-pyrazinedithiol. These complexes are non-innocent and possess strong electronic coupling between ligands across the metal center. The electronic coupling can be readily quantified in the monoanionic mixed valence state using Marcus-Hush theory. Analysis of the intervalence charge transfer (IVCT) band reveals that that electronic coupling in the mixed valence state is 5800, 4500, and 5700 cm(-1) for the Ni, Pd, and Pt complexes, respectively. We then focus on their response to acid titration in the mixed valence state, which generates the asymmetrically protonated mixed valence mixed protonated state. For all three complexes, protonation results in severe attenuation of the electronic coupling, as measured by the IVCT band. We find nearly 5-fold decreases in electronic coupling for both Ni and Pt, while, for the Pd complex, the electronic coupling is reduced to the point that the IVCT band is no longer observable. We ascribe the reduction in electronic coupling to charge pinning induced by asymmetric protonation. The more severe reduction in coupling for the Pd complex is a result of greater energetic mismatch between ligand and metal orbitals, reflected in the smaller electronic coupling for the pure mixed valence state. This work demonstrates that the bridging metal center can be used to tune the electronic coupling in both the mixed valence and mixed valence mixed protonated states, as well as the magnitude of change of the electronic coupling that accompanies changes in protonation state.
DOI：
10.1021/jp805876e
发表时间：
2008-11-13
期刊：
The journal of physical chemistry. B
影响因子：
--
作者：
Hammes-Schiffer S;Soudackov AV
通讯作者：
Soudackov AV