Synthesis and Characterization of Paramagnetic Tungsten Imido Complexes Bearing α-Diimine Ligands

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• 作者：Hiromasa Tanahashi ; Hideaki Ikeda ; Hayato Tsurugi ; Kazushi Mashima
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：February 15, 2016
• 年：2016
• 卷：55
• 期：4
• 页码：1446-1452
• 全文大小：422K
• ISSN：1520-510X

文摘

Tungsten imido complexes bearing a redox-active ligand, such as N,N′-bis(2,6-diisopropylphenyl)-1,4-diaza-2,3-dimethyl-1,3-butadiene (L1), N,N′-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene (L2), and 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (L3), were prepared by salt-free reduction of W(═NC₆H₃-2,6-ⁱPr₂)Cl₄ (1) using 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene (MBTCD) followed by addition of the corresponding redox-active ligands. In the initial stage, reaction of W(═NC₆H₃-2,6-ⁱPr₂)Cl₄ with MBTCD afforded a tetranuclear W(V) imido cluster, [W(═NC₆H₃-2,6-ⁱPr₂)Cl₃]₄ (2), which served as a unique precursor for introducing redox-active ligands to the tungsten center to give the corresponding mononuclear complexes with a general formula of W(═NC₆H₃-2,6-ⁱPr₂)Cl₃(L) (3, L = L1; 4, L = L2; and 6, L = L3). X-ray analyses of complexes 3 and 6 revealed a neutral coordination mode of L1 and L3 to the tungsten in solid state, while the electron paramagnetic resonance (EPR) spectra of 3 and 4 clarified that a radical was predominantly located on the tungsten center supported by neutral L1 or L2, and the EPR spectra of complex 6 indicated that a radical was delocalized over both the tungsten center and the monoanionic redox-active ligand L3.