Bis-Ferrocenyl-Pyridinediimine Trinuclear Mixed-Valent Complexes with Metal-Binding Dependent Electronic Coupling: Synthesis, Structures, and Redox-Spectroscopic Characterization
Bis-Ferrocenyl-Pyridinediimine Trinuclear Mixed-Valent Complexes with Metal-Binding Dependent Electronic Coupling: Synthesis, Structures, and Redox-Spectroscopic Characterization
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DOI：
10.1021/jacs.0c10015
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发表时间：
2020-10-28
影响因子：
15
通讯作者：
Marks, Tobin J.
中科院分区：
文献类型：
--
作者：
Carter, Cole;Kratish, Yosi;Marks, Tobin J.
系统地合成了具有双二茂铁基取代的吡啶二亚胺配体的金属二氯化物配合物家族（（Fc（2）PDI）MCl 2，M = Mg、Zn、Fe和Co），并通过晶体学、光谱学、电化学和计算进行表征。配体二茂铁单元之间的电子耦合在与MCl 2片段结合时被打开，如循环伏安法中二茂铁的两个顺序氧化所证明的（Δ E-ox约为200 mV）和近IR中的价间电荷转移电子激发。此外，紫外-可见光谱用于直接观察二茂铁基单元和亚胺π系统之间的轨道混合，因为轨道对称性破缺导致允许的跃迁（c = 2800 M-1 cm（-1），自由二茂铁中c约为200 M-1 cm（-1））以及二茂铁基跃迁的加宽和红移--表明以前纯金属中心跃迁的有机特征。DFT分析表明，二茂铁和MCl 2片段之间的相互作用是小的，并表明通信介导的二茂铁和有机π * 轨道之间的更好的能量匹配后，协调，允许通过LUMO超交换耦合。此外，从一个和两个二茂铁的氧化得到的单晶衍射数据显示失真，引入空的d（xy）/d（x2-y2）轨道到次级配位球的MCl 2片段。这种结构重排是罕见的二茂铁基mixedvaluate化合物，催化以及电子通信的影响进行了讨论。
A family of metal dichloride complexes having a bis-ferrocenyl-substituted pyridinediimine ligand was systematically synthesized ((Fc(2)PDI)MCl2, M = Mg, Zn, Fe, and Co) and characterized crystallographically, spectroscopically, electrochemically, and computationally. Electronic coupling between the ligand ferrocene units is switched on upon binding to a MCl2 fragment, as evidenced by both sequential oxidation of the ferrocenes in cyclic voltammetry (Delta E-ox approximate to 200 mV) and by Inter-Valence Charge Transfer electronic excitations in the near IR. Additionally, UV-vis spectra are used to directly observe orbital mixing between the ferrocenyl units and the imine pi system since breaking of the orbital symmetry results in allowed transitions (c = 2800 M-1 cm(-1) vs c approximate to 200 M-1 cm(-1) in free ferrocene) as well as broadening and red-shifting of the ferrocenyl transitions-indicating organic character in formerly pure metal-centered transitions. DFT analysis reveals that interaction between the ferrocenes and the MCl2 fragment is small and suggests that communication is mediated by better energy matching between the ferrocene and organic pi* orbitals upon coordination, allowing superexchange coupling through the LUMO. Furthermore, single crystal diffraction data obtained from oxidation of one and both ferrocenes show distortions, introducing the empty d(xy)/d(x2-y2) orbitals into the secondary coordination sphere of the MCl2 fragment. Such structural rearrangements are infrequent in ferrocenyl mixedvalent compounds, and implications for catalysis as well as electronic communication are discussed.