Keilwerth Martin, Grunwald Liam, Mao Weiqing, Heinemann Frank W, Sutter Jörg, Bill Eckhard, Meyer Karsten
Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058 Erlangen, Germany.
Max-Planck-Institut für Chemische Energiekonversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany.
J Am Chem Soc. 2021 Jan 27;143(3):1458-1465. doi: 10.1021/jacs.0c11141. Epub 2021 Jan 12.
A new supporting ligand, -[2-(3-mesityl-idazol-2-ylidene)ethyl]amie (TIMMN), was developed and utilized to isolate an air-stable iron(V) complex bearing a terminal nitrido ligand, which was synthesized by one-electron oxidation from the iron(IV) precursor. Single-crystal X-ray diffraction analyses of both complexes reveal that the metal-centered oxidation is escorted by iron nitride (Fe≡N) bond elongation, which in turn is accompanied by the accommodation of the high-valence iron center closer to the equatorial plane of a trigonal bipyramid. This contrasts with the previous observation of the only other literature-known Fe(IV)≡N/Fe(V)≡N redox pair, namely, [PhB(Im)FeN]. On the basis of Fe Mössbauer, EPR, and UV/vis electronic absorption spectroscopy as well as quantum chemical calculations, we identified the lesser degree of pyramidalization around the iron atom, the Jahn-Teller distortion, and the resulting nature of the SOMO to be the decisive factors at play.
一种新型支持配体——-[2-(3-均三甲苯基-咪唑-2-亚基)乙基]胺(TIMMN)被开发并用于分离一种带有末端氮化物配体的空气稳定的铁(V)配合物，该配合物由铁(IV)前体通过单电子氧化合成。两种配合物的单晶X射线衍射分析表明，以金属为中心的氧化伴随着氮化铁(Fe≡N)键的伸长，而这又伴随着高价铁中心向三角双锥赤道平面的靠近。这与之前观察到的唯一另一篇文献报道的Fe(IV)≡N/Fe(V)≡N氧化还原对，即[PhB(Im)FeN]形成对比。基于Fe穆斯堡尔谱、电子顺磁共振谱以及紫外/可见电子吸收光谱和量子化学计算，我们确定铁原子周围较小程度的锥化、 Jahn-Teller畸变以及由此产生的单占据分子轨道的性质是起决定性作用的因素。
