Redox-Active Ferrocene as a Tuning Functionality for Magnetic Superexchange Interactions of Bis(oxamato) Type Complexes

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• 作者：Mohammad A. Abdulmalic ; Azar Aliabadi ; Andreas Kurt Petr ; Yulia Krupskaya ; Vladislav Kataev ; Bernd B眉chner ; Torsten Hahn ; Jens Kortus ; Nicolas Y猫che ; Hans-Henning Klauss ; Tobias R眉ffer
• 刊名：Organometallics
• 出版年：2013
• 出版时间：October 28, 2013
• 年：2013
• 卷：32
• 期：20
• 页码：5988-6003
• 全文大小：790K
• 年卷期：v.32,no.20(October 28, 2013)
• ISSN：1520-6041

文摘

The reaction of 1,1鈥?diaminoferrocene with two equivalents of ethyloxalyl chloride in THF afforded the diethyl ester of N,N鈥?ferrocenylenebis(oxamic acid) (1,1鈥?fcbaH₂Et₂, 1). 1 was converted readily to its saponificated form only, namely [ⁿBu₄N]₂[(1,1鈥?fcbaH₂)] (2), when treated with 4 equiv of [ⁿBu₄N]OH followed by the subsequent addition of [Ni(H₂O)₆]Cl₂, whereas [ⁿBu₄N]₂[Cu(1,1鈥?fcba)] (3) was obtained in ca. 70% yield by using CuCl₂路2H₂O. Oxidation of 3 with I₂ led to the formation of [ⁿBu₄N][Cu(1,1鈥?fcba)] (4). A combined study of 4 by ESR and ⁵⁷Fe M枚ssbauer spectroscopy, supported by DFT calculations, revealed the iron atom of 4 to possess the oxidation state +3. Treatment of 1 with MeNH₂ resulted in the exclusive formation of the methyl ester of ferrocenylene-1-(N-methyloxamide)-1鈥?(oxamic acid) (1,1鈥?fcooH₃Me₂, 5). Successive treatment of 5 with [Cu₂(OAc)₄(H₂O)₂] and [ⁿBu₄N]OH gave rise to the formation of [ⁿBu₄N]₂[Cu(fcooMe)]路2H₂O (6A路2H₂O and 6B路2H₂O), for which single crystals of the compositions [ⁿBu₄N]₂[Cu(1,1鈥?fcooMe)]路¹/₂MeOH路¹/₂H₂O (6A路¹/₂MeOH路¹/₂H₂O) and [ⁿBu₄N]₂[Cu(1,1鈥?fcooMe)]路2.25H₂O (6B路2.25H₂O) were grown. Single-crystal X-ray diffraction studies revealed 6A路¹/₂MeOH路¹/₂H₂O and 6B路2.25H₂O to contain [Cu(fcooMe)]^{2鈥?/sup> fragments in the form of two different conformers, having a significant difference in their total energy, as found by DFT calculations. Treatment of 3 and 4, respectively, with [Cu(pmdta)(NO₃)₂] afforded the tetranuclear complexes [Cu₃(1,1鈥?fcba)(pmdta)₂](NO₃)_n (n = 2 (7), 3 (8)). The solid-state structures of 1鈥?b>3, 7, and 8 were determined by single-crystal X-ray diffraction studies. The magnetic properties of 3, 4, 7, and 8 were studied by susceptibility measurements versus temperature. For 4 a weak antiferromagnetic coupling between the CuII and FeIII ions has been obtained with J = 鈭? cm鈥?, whereas 3 can be understood as a purely paramagnetic, CuII/FeII-containing complex only. For 7 a J parameter of 鈭?8 cm鈥? has been obtained due to an antiferromagnetic interaction between its CuII ions. This magnetic exchange interaction modifies in 8 to 鈭?4 cm鈥?, and an additional ferromagnetic coupling of 4 cm鈥? between the FeIII ion and the central CuII ion is obtained.}