Amidinium-Containing 2D [MnCr] Dimetallic Oxalate-Based Networks - The Influence on Structure and Magnetism Explored by Combining Experience and Theory

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• 作者：Catalin Maxim ; Sergi Saureu ; Coen de Graaf ; Sylvie Ferlay ; Mir Wais Hosseini ; Vincent Robert and Cyrille Train
• 刊名：European Journal of Inorganic Chemistry
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：2016
• 期：26
• 页码：4185-4193
• 全文大小：2203K
• ISSN：1099-0682c

文摘

Three X²⁺ bisamidinium dications are inserted into oxalate-based dimetallic [MnCr] compounds of formula X[Mn^II(CH₃OH)Cr^III(ox)₃]₂·nS [X²⁺ = C₁₄N₄H₂₀²⁺ (cation A²⁺, compound 1), C₁₄O₂N₄H₂₀²⁺ (cation B²⁺, compound 2), C₁₆N₄H₂₄²⁺ (cation C²⁺, compound 3); n = 4 (1–2), 2 (3); S = CH₃OH (1–2), CH₃CN (3); ox = oxalate]. Single-crystal X-ray analysis of 1–3 reveals that Mn–Cr oxalate-bridged dimetallic coordination networks form corrugated two-dimensional (2D) layers based on heptacoordinate Mn^II ions surrounded by six oxygen atoms from three bis-bidentate oxalate ions and one oxygen atom from a coordinated methanol molecule. In 1–3, the observed coordination environments of the Mn^II ions are close to capped trigonal prismatic (CTPR-7) according to continuous shape measurements (CSM). Curie–Weiss temperatures of 0.62, 0.42, and 0.54 K for 1–3, respectively, were deduced from the magnetic susceptibility measurements and reveal dominant ferromagnetic exchange interactions. Ab initio calculations up to the DDCI-2 level were performed on [MnCr] dimeric units and allowed the evaluation of the exchange interactions in 1–3.