High-spin tetranuclear iron(III) grids: Synthesis, crystal structure and magnetic properties

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• 作者：Yi-Tong Wang ; Ai-Li Cui ; De-Zhong Shen ; Hui-Zhong Kou ; ^{kouhz@mail.tsinghua.edu.cn}
• 关键词：Fe(III) ions ; Magnetic properties ; Crystal structure ; Grid ; Tetranuclear complexes
• 刊名：Polyhedron
• 出版年：2013
• 出版时间：22 March, 2013
• 年：2013
• 卷：52
• 期：Complete
• 页码：970-975
• 全文大小：531 K

文摘

Three new tetranuclear Fe^III complexs Fe₄L¹₄Cl₄ (1), Fe₄L²₄(ClO₄)₄ (2), Fe₄L³₄Cl₄5H₂O (3) and a binuclear complex Fe₂L⁴(MeOH)₂Cl₄3MeOH (4) (the bis-Schiff base ligands H₂L^1-4 were obtained by the condensation of 2,4-dihydrazinopyrimidine and salicylicaldehyde or acetylacetone in a molar ratio of 1:2) have been synthesized and characterized by crystallography, spectroscopy and magnetic measurements. The tetranuclear 2 ¡Á 2 grid complex 1 crystallizes in a monoclinic space group C2/c with a = 29.040(3) ?, b = 10.9525(11) ?, c = 26.881(3) ?, ¦Â = 105.172(2)¡ã, V = 8251.9(15) ?³. Complex 2 crystallizes in a monoclinic space group P2₁ with a = 12.536(3) ?, b = 23.148(5) ?, c = 17.506(4) ?, ¦Â = 102.96(3)¡ã, V = 4950.6(17) ?³, and complex 3 in a triclinic space group with a = 12.145(2) ?, b = 29.094(6) ?, c = 29.343(6) ?, ¦Á = 94.12(3)¡ã, ¦Â = 93.17(3)¡ã, ¦Ã = 97.62(3)¡ã, V = 10228(4) ?³. All the Fe^III ions from 1, 2 and 3 are coordinated by an N₄O₂ sphere with two N atoms from pyrimidine, two N atoms from hydrazine, and two O atoms from phenoxo groups. Complex 4 has a binuclear structure crystallized in a triclinic space group with a = 10.500(2) ?, b = 11.053(2) ?, c = 15.990(3) ?, ¦Á = 82.20(3)¡ã, ¦Â = 89.64(3)¡ã, ¦Ã = 70.77(3)¡ã, V = 1734.4(6) ?³. Magnetic susceptibility measurements indicate that the Fe(III) ions are all high spin, and adjacent Fe(III) ions are weakly antiferromagnetically coupled via pyrimidine in complexes 1, 2, 3 and 4. Magneto-structural correlation studies show that a longer Fe-N_pym bond distance corresponds to a weaker antiferromagnetic coupling.