1,1′-Bis(pyrazol-4-yl)ferrocenes: Potential Clip Ligands and Their Supramolecular Structures

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• 作者：Mattia Veronelli ; Sebastian Dechert ; Anne Schober ; Serhiy Demeshko and Franc Meyer
• 刊名：European Journal of Inorganic Chemistry
• 出版年：2017
• 出版时间：January 10, 2017
• 年：2017
• 卷：2017
• 期：2
• 页码：446-453
• 全文大小：1387K
• ISSN：1099-0682c

文摘

Two ferrocene derivatives with pyrazoles appended at their C-4 position to both cyclopentadienyl (Cp) rings have been synthesized, namely, 1,1′-bis(1H-pyrazol-4-yl)ferrocene (H₂^HL) and 1,1′-bis(3,5-dimethyl-1H-pyrazol-4-yl)ferrocene (H₂^MeL). In the solid state, these are shown crystallographically to form supramolecular aggregates through intermolecular NH···N hydrogen bonds in either a dimeric (H₂^HL) or trimeric (H₂^MeL) arrangement. Variable-temperature NMR spectroscopy and diffusion-ordered spectroscopy (DOSY) evidenced the presence of [H₂^MeL]₃ trimers in [D₈]toluene solution, whereas both H₂^HL and H₂^MeL exist as monomers in deuterated N,N-dimethylformamide ([D₇]DMF) even at low temperatures. The kinetic parameters for the NH tautomerism have been determined. In their dianionic forms, both of these hybrid ferrocene/pyrazole molecules serve as ligands towards Cu^I, Ag^I, and Au^I ions. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) revealed the formation of [M₂^RL]₃ hexametallic complexes, the structures of which are suggested to have D_3h symmetry with two metallomacrocyclic [M(µ-pz)]₃ (pz = pyrazolate) decks connected by three ferrocene clips. Mössbauer spectra and preliminary luminescence data were collected for the proligands and the resulting complexes. Owing to the insolubility of the coinage-metal complexes, the electrochemical properties could be measured only for the two H₂^RL proligands.