Structure and Antiferromagnetism of Trinuclear Heterometallic Strings Containing Mn^II-M^II-Mn^II Frameworks (M = Ni, Pd, Pt)

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• 作者：Li-Chung Yu ; Gene-Hsiang Lee ; Marc Sigrist ; Tien-Sung Lin and Shie-Ming Peng
• 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：4250-4256
• 全文大小：912K
• ISSN：1099-0682c

文摘

The syntheses, crystal structures, and magnetic properties of three trinuclear, symmetric, heterometal string complexes stabilized by four dipyridylamide (dpa) ligands were explored. MnNiMn(dpa)₄Cl₂ (1), MnPdMn(dpa)₄Cl₂ (2), and MnPtMn(dpa)₄Cl₂ (3) were found to exhibit an approximate D₄ symmetry and a linear metal framework helically wrapped by four syn–syn-type ligands. The center metal ions bond with the amide part of dpa^– in a square-planar environment, and the outer Mn ions bond with Cl^– and the pyridyl part of dpa^– in a square-pyramidal environment. The magnetic susceptibilities of these three compounds showed antiferromagnetic interactions (2J = –13.7 cm^–1 for 1, –29.7 cm^–1 for 2, and –66.2 cm^–1 for 3 in the Heisenberg exchange framework) between the MnII magnetic centers. The value of 2J increased with increasing atomic number of the central metal ion. The antiferromagnetic properties were further confirmed by electron paramagnetic resonance spectroscopy studies in variable-temperature measurements.