Mohapatra Swagat K, Fonari Alexandr, Risko Chad, Yesudas Kada, Moudgil Karttikay, Delcamp Jared H, Timofeeva Tatiana V, Brédas Jean-Luc, Marder Seth R, Barlow Stephen
School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA 30332-0400 (USA); Present address: KIIT University, Bhubaneswar, Orissa 751024 (India).
Chemistry. 2014 Nov 17;20(47):15385-94. doi: 10.1002/chem.201404007. Epub 2014 Oct 3.
The dimers of some Group 8 metal cyclopentadienyl/arene complexes and Group 9 metallocenes can be handled in air, yet are strongly reducing, making them useful n-dopants in organic electronics. In this work, the X-ray molecular structures are shown to resemble those of Group 8 metal cyclopentadienyl/pentadienyl or Group 9 metal cyclopentadienyl/diene model compounds. Compared to those of the model compounds, the DFT HOMOs of the dimers are significantly destabilized by interactions between the metal and the central CC σ-bonding orbital, accounting for the facile oxidation of the dimers. The lengths of these CC bonds (X-ray or DFT) do not correlate with DFT dissociation energies, the latter depending strongly on the monomer stabilities. Ru and Ir monomers are more reducing than their Fe and Rh analogues, but the corresponding dimers also exhibit much higher dissociation energies, so the estimated monomer cation/neutral dimer potentials are, with the exception of that of [RhCp2 ]2 , rather similar (-1.97 to -2.15 V vs. FeCp2 (+/0) in THF). The consequences of the variations in bond strength and redox potentials for the reactivity of the dimers are discussed.
一些第8族金属环戊二烯基/芳烃配合物和第9族金属茂的二聚体在空气中可以处理，但具有很强的还原性，这使得它们在有机电子学中成为有用的n型掺杂剂。在这项工作中，X射线分子结构显示与第8族金属环戊二烯基/戊二烯基或第9族金属环戊二烯基/二烯模型化合物的结构相似。与模型化合物相比，二聚体的密度泛函理论（DFT）最高已占分子轨道（HOMO）因金属与中心CC σ键轨道之间的相互作用而显著失稳，这解释了二聚体易于氧化的原因。这些CC键的长度（X射线或DFT）与DFT离解能无关，后者强烈依赖于单体的稳定性。钌和铱单体比它们的铁和铑类似物具有更强的还原性，但相应的二聚体也表现出高得多的离解能，因此，除了[RhCp2 ]2 之外，估计的单体阳离子/中性二聚体电位相当相似（在四氢呋喃中相对于FeCp2 (+/0)为-1.97至-2.15 V）。讨论了键强度和氧化还原电位变化对二聚体反应性的影响。
