Department of Chemistry , Yale University , 225 Prospect Street , New Haven , Connecticut 06520 , United States.
Hylleraas Center for Quantum Molecular Sciences, Department of Chemistry , University of Oslo , P.O. Box 1033, Blindern , 0315 Oslo , Norway.
Inorg Chem. 2018 May 7;57(9):5684-5691. doi: 10.1021/acs.inorgchem.8b00757. Epub 2018 Apr 10.
We report a general method for the preparation and crystallization of highly oxidized metal complexes that are difficult to prepare and handle by more conventional means. This method improves typical bulk electrolysis and crystallization conditions for these reactive species by substituting oxidation-prone organic electrolytes and precipitants with oxidation-resistant compounds. Specifically, we find that CsPF is an effective inert electrolyte in acetonitrile, and appears to have general applicability to electrochemical studies in this solvent. Likewise, CCl is not only an oxidation-resistant precipitant for crystallization from MeCN but it also enters the lattice. In this way, we synthesized and characterized an Ir(V,V) mono-μ-oxo dimer which only forms at a very high potential (1.9 V vs NHE). This compound, having the highest isolated oxidation state in this redox-active system, cannot be formed chemically. DFT calculations show that the oxidation is centered on the Ir-O-Ir core and facilitated by strong electron-donation from the pyalk (2-(2-pyridinyl)-2-propanolate) ligand. TD-DFT simulations of the UV-visible spectrum reveal that its royal blue color arises from electron excitations with mixed LMCT and Laporte-allowed d-d character. We have also crystallographically characterized a related monomeric Ir(V) complex, similarly prepared by oxidizing a previously reported Ir(IV) compound at 1.7 V, underscoring the general applicability of this method.
我们报道了一种通用的方法，用于制备和结晶高度氧化的金属配合物，这些配合物很难通过更传统的方法来制备和处理。这种方法通过用不易氧化的化合物替代易氧化的有机电解质和沉淀剂来改善这些反应性物质的典型批量电解和结晶条件。具体来说，我们发现 CsPF 在乙腈中是一种有效的惰性电解质，并且似乎在该溶剂中的电化学研究中具有普遍适用性。同样，CCl 不仅是从 MeCN 结晶的不易氧化的沉淀剂，而且还进入晶格。通过这种方式，我们合成并表征了一种 Ir(V,V)单核μ-氧二聚体，它只能在非常高的电位（1.9 V 相对于 NHE）下形成。这种化合物在这个氧化还原活性体系中具有最高的孤立氧化态，不能通过化学方法形成。DFT 计算表明，氧化中心位于 Ir-O-Ir 核上，并且受到来自 pyalk（2-(2-吡啶基)-2-丙醇盐）配体的强电子供体的促进。UV-可见光谱的 TD-DFT 模拟表明，其皇家蓝色是由于电子激发具有混合 LMCT 和 Laporte 允许的 d-d 特征。我们还通过在 1.7 V 下氧化先前报道的 Ir(IV)化合物来结晶地表征了一种相关的单核 Ir(V)配合物，这突出了这种方法的普遍适用性。
