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Anion-driven supramolecular modulation of spin-crossover properties in mononuclear iron(III) Schiff-base complexes.

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Title: Anion-driven supramolecular modulation of spin-crossover properties in mononuclear iron(III) Schiff-base complexes.
Authors: Yu, Zong-Mei1 (AUTHOR), Zhao, Sheng-Ze1 (AUTHOR), Wang, Yu-Ting1 (AUTHOR), Xu, Peng-Yu1 (AUTHOR), Qin, Chun-Yan1 (AUTHOR), Li, Yong-Hua1 (AUTHOR) iamswang@njupt.edu.cn, Zhou, Xin-Hui1 (AUTHOR), Wang, Shi1 (AUTHOR)
Source: Dalton Transactions: An International Journal of Inorganic Chemistry. 11/14/2021, Vol. 50 Issue 42, p15210-15223. 14p.
Subjects: Space groups, Isomorphous structures, Magnetic susceptibility, Magnetic measurements, Crystal structure
Abstract: A series of Fe(III) complexes [Fe(5-F-sal-N-1,4,7,10)]Y (Y = PF6− for 1, Y = ClO4− for 2, Y = I− for 3 and Y = NO3− for 4) have been prepared. Single-crystal X-ray crystallographic studies show that complex 1 crystallizes in the orthorhombic Pna21 space group and complexes 2–4 have an isomorphous structure and crystallize in the same monoclinic space group, P21/n. Complexes 2–4 have two independent molecules (Fe1 and Fe2) in the unit cell. Magnetic susceptibility measurements demonstrated that complexes 1 and 3 showed a gradual one-step SCO behavior (T1/2 for 1 = 177 K and for 3 = 227 K) without thermal hysteresis. The magnetic behavior of 2 shows an incomplete two-step SCO process at T1/2 = 114 K and 170 K, respectively, while 4 is in a high-spin state at all measured temperatures. A careful evaluation of the supramolecular structures of these complexes revealed correlation between the supramolecular packing forces and their SCO behavior. The crystal structure of 1 consists of a three-dimensional (3D) extended network constructed from N–H⋯F and C–H⋯F hydrogen bonds, and C–H⋯π and C⋯C short contacts. In compounds 2–4, the crystal packing is governed by C⋯C, C–H⋯π and p–π interactions for the Fe1 centers and by C–H⋯π/O interactions for the Fe2 centers, which form 1D chains. Additional interactions (C–H⋯F and N–H⋯O/I) connect the neighboring chains and planes to form a complex supramolecular network. The anion⋯π interactions in 4 provide a means for preventing SCO occurring at low temperatures. This suggests that the supramolecular connectivity of the anions influences the magnetic properties. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:A series of Fe(III) complexes [Fe(5-F-sal-N-1,4,7,10)]Y (Y = PF6− for 1, Y = ClO4− for 2, Y = I− for 3 and Y = NO3− for 4) have been prepared. Single-crystal X-ray crystallographic studies show that complex 1 crystallizes in the orthorhombic Pna21 space group and complexes 2–4 have an isomorphous structure and crystallize in the same monoclinic space group, P21/n. Complexes 2–4 have two independent molecules (Fe1 and Fe2) in the unit cell. Magnetic susceptibility measurements demonstrated that complexes 1 and 3 showed a gradual one-step SCO behavior (T1/2 for 1 = 177 K and for 3 = 227 K) without thermal hysteresis. The magnetic behavior of 2 shows an incomplete two-step SCO process at T1/2 = 114 K and 170 K, respectively, while 4 is in a high-spin state at all measured temperatures. A careful evaluation of the supramolecular structures of these complexes revealed correlation between the supramolecular packing forces and their SCO behavior. The crystal structure of 1 consists of a three-dimensional (3D) extended network constructed from N–H⋯F and C–H⋯F hydrogen bonds, and C–H⋯π and C⋯C short contacts. In compounds 2–4, the crystal packing is governed by C⋯C, C–H⋯π and p–π interactions for the Fe1 centers and by C–H⋯π/O interactions for the Fe2 centers, which form 1D chains. Additional interactions (C–H⋯F and N–H⋯O/I) connect the neighboring chains and planes to form a complex supramolecular network. The anion⋯π interactions in 4 provide a means for preventing SCO occurring at low temperatures. This suggests that the supramolecular connectivity of the anions influences the magnetic properties. [ABSTRACT FROM AUTHOR]
ISSN:14779226
DOI:10.1039/d1dt02394b