Linear and T-Shaped Iron(I) Complexes Supported by N-Heterocyclic Carbene Ligands: Synthesis and Structure Characterization

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• 作者：Zhenwu Ouyang ; Jingzhen Du ; Lei Wang ; Jared L. Kneebone ; Michael L. Neidig ; Liang Deng
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：September 8, 2015
• 年：2015
• 卷：54
• 期：17
• 页码：8808-8816
• 全文大小：497K
• ISSN：1520-510X

文摘

The use of the N-heterocyclic carbene (NHC) ligands 1,3-bis(2鈥?6鈥?diethylphenyl)-4,5-(CH₂)₄-imidazol-2-ylidene (cyIDep), 1,3-bis(2鈥?6鈥?diethylphenyl)-imidazolin-2-ylidene (sIDep), and its N-mesityl analogue sIMes enables the preparation of the two-coordinate homoleptic iron(I)-NHC complexes [(cyIDep)₂Fe][BAr^F₄] (3, Ar^F denoted for 3,5-di(trifluoromethyl)phenyl) and [(sIDep)₂Fe][BAr^F₄] (4) and the T-shaped iron(I)-NHC complex [(sIMes)₂Fe(THF)][BPh₄] (5, THF = tetrahydrofuran). Complexes 3鈥?b>5 were prepared via the sequential protocol of control reduction of iron(II) dihalides by KC₈ in the presence of the corresponding NHC ligands followed by halide-abstraction with NaBAr₄. Spectroscopic characterization, including single-crystal X-ray diffraction studies and ⁵⁷Fe M枚ssbauer spectroscopy, in combination with density functional theory calculations, suggest their high-spin nature. Solution property study (absorption spectroscopy and cyclic voltammetry) indicates that 3 and 5 keep their corresponding two- and three-coordinate nature in THF solution, and 4 might reversibly coordinate a THF molecule to form, presumably, the T-shaped species [(sIDep)₂Fe(THF)][BAr^F₄]. The isolation of 3 and 4 demonstrates the accessibility of homoleptic two-coordinate iron(I)-NHC complexes.