Synthesis of Aryl-Substituted Bis(imino)pyridine Iron Dinitrogen Complexes

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• 作者：Sarah K. Russell ; Jonathan M. Darmon ; Emil Lobkovsky ; Paul J. Chirik
• 刊名：Inorganic Chemistry
• 出版年：2010
• 出版时间：March 15, 2010
• 年：2010
• 卷：49
• 期：6
• 页码：2782-2792
• 全文大小：997K
• 年卷期：v.49,no.6(March 15, 2010)
• ISSN：1520-510X

文摘

The synthesis and characterization of dimeric, aryl-substituted bis(imino)pyridine iron dinitrogen complexes is described. In contrast to reduction with sodium amalgam where bis(chelate) iron compounds were isolated, stirring (^ArPDI)FeBr₂ or (^MeBPDI)FeBr₂ (PDI = 2,6-(ArN═CMe)₂C₅H₃N; Ar = 2,6-Et₂-C₆H₃N (^EtPDI), 2,6-Me₂-C₆H₃N (^MePDI), 2-ⁱPr,6-Me-C₆H₃N (^Me,iPrPDI); ^MeBPDI = 2,6-(2,6-Me₂-C₆H₃N═CPh)₂C₅H₃N) with sodium naphthalenide resulted in isolation of the desired iron dinitrogen compounds as diamagnetic solids. Two examples, [(^EtPDI)Fe(N₂)]₂(μ₂-N₂) and [(^MeBPDI)Fe(N₂)]₂(μ₂-N₂), were characterized by X-ray diffraction. The solid state metrical parameters, in combination with infrared and Mssbauer spectroscopic data, establish ferrous compounds with doubly reduced chelates. Each new bis(imino)pyridine iron dinitrogen compound was screened for the catalytic hydrogenation of ethyl-3-methylbut-2-enoate, and the compound bearing the smallest aryl substituent, [(^MePDI)Fe(N₂)]₂(μ₂-N₂), offers significant improvement over the original (^iPrPDI)Fe(N₂)₂ pre-catalyst and is one of the most active iron pre-catalysts known.