Magnetic Ordering in Three-Dimensional Metal鈥揙rganic Frameworks Based on Carboxylate Bridged Square-Grid Layers

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• 作者：Qian Sun ; Ai-ling Cheng ; Yan-Qin Wang ; Yu Ma ; En-Qing Gao
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：September 5, 2011
• 年：2011
• 卷：50
• 期：17
• 页码：8144-8152
• 全文大小：987K
• 年卷期：v.50,no.17(September 5, 2011)
• ISSN：1520-510X

文摘

Three isomorphous metal鈥搊rganic frameworks of formula [M(ppdc)(H₂O)₂]_n [M = Mn(II), Fe(II), and Co(II)] were synthesized from sodium p-phenylenediacrylic (Na₂ppdc). Crystallographic studies revealed that the compounds are layer-pillared 3D frameworks in which the square-grid M(II) layers with single carboxylate bridges are interlinked by long organic spacers with large interlayer separations of about 13 脜. Magnetic investigations indicated that they all display intralayer antiferromagnetic interactions through the carboxylate bridges in the unusual skew鈥搒kew coordination mode but the bulk behaviors are quite different. The Co(II) compound, like most compounds containing similar M鈥揙鈥揅鈥揙鈥揗 layers, shows no 3D magnetic ordering down to 2 K, while the Mn(II) and Fe(II) compounds exhibit spin-canted ordering, behaving as a weak ferromagnet (T_C = 3.8 K) and a metamagnet (T_N = 3.8 K, H_c = 650 Oe), respectively. Spin-canted ordering is still a rarity in this series of materials. Magnetostructural comparisons with analogous compounds indicate that the occurrence of spin-canted ordering can be related to the uncommon skew鈥搒kew and anti鈥揳nti coordination modes of carboxylate bridges, which induce stronger antiferromagnetic interactions than the common syn鈥揳nti mode.