H-bonding directed formation of 1D-single chains, 2D-sheets, and 3D structures in magnetically coupled tetranuclear nickel(II) complexes with incomplete double cubane core

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• 作者：Santokh S. Tandon^a ; ^b ; ^{standon@kent.edu} ; Scott D. Bunge^b ; Neil Patel^b ; Joaquin Sanchiz^c
• 关键词：Tetranuclear nickel complexes ; Ferromagnetically coupled tetranuclear nickel complexes ; Nickel complexes of Schiff base ligands ; Coordination polymers ; Structures of tetranuclear nickel complexes
• 刊名：Polyhedron
• 出版年：2017
• 出版时间：17 February 2017
• 年：2017
• 卷：123
• 期：Complete
• 页码：361-375
• 全文大小：4038 K
• 卷排序：123

文摘

Reactions of 2,6-diformyl-4-methylphenol (DFMF) with 1-amino-2-propanol (AP) and 2-amino-1,3-propanediol (APD) in the presence of nickel(II) salts, NiX2 (X = CH3CO2−, NO3−, Cl−, ClO4−, BF4−)/sodium azide (NaN3), and triethylamine (TEA), in one pot self-assemble giving tetranuclear coordination complexes of nickel(II) with an incomplete double cubane structural core: [Ni4(H2L−1)2(μ-CH3CO2)2(μ3-X)2(μ-1,1-N3)2]·2CH3OH {X = 1,1,1-N3 (1A) and OCH3 (1B)}, [Ni4(H2L−1)2(μ-1,1-N3)2(N3)2(μ3-OCH3)2 (H2O)2] (2), [Ni4(H2L−1)2(μ3-1,1,1-N3)2(μ-1,1-N3)2(CH3OH)2Cl2]·4CH3OH (3), [Ni4(H4L1−1)2(μ3-1,1,1-N3)2(μ-1,1-N3)2(CH3OH)2(OH)2]·2H2O (4), and [Ni4(HL2−2)2(APD−1)2][ClO4]2·2H2O·2CH3OH (5). In 1–3, H2L−1, in 4, H4L1−1, and in 5, HL22− represent a singly deprotonated chiral, potentially pentadentate trianionic double Schiff base ligand, H3L; a singly deprotonated potentially heptadentate pentaanionic double Schiff base ligand, H5L1; and a doubly deprotonated potentially tetradentate trianionic single Schiff base ligand, H3L2 respectively. In 1A, 3, and 4 two dinickel (Ni2) units are connected through two doubly bridging end-on (EO) μ-azido and two triply bridging EO μ3-azido bridges and in 2, though two EO μ-azido and two μ3-1,1,1-methoxy bridges generating tetranuclear units. In each dinuclear unit two nickel centers are bridged through one μ-phenolate oxygen from H2L−1, one μ-CH3CO2−, and one EO μ3-azido nitrogen (1) and through one μ-phenolate oxygen from H2L−1/H4L1−1 and one μ3-methoxy oxygen (2)/one μ3-azido nitrogen (3 and 4). In 5, two nickel(II) ions in the dinuclear unit are bridged though phenoxide oxygen and alkoxide oxygen bridges and two dinuclear units are interconnected via six symmetry related alkoxide bridges forming tetranickel units. In 1–4 neutral tetranuclear [Ni4] units and in 5, cationic tetranickel [Ni4]2+ units are interconnected by a symmetrical network of H-bonding between coordinated/uncoordinated hydroxido groups in the side arms of the double Schiff-base ligands, coordinated hydroxide ion/chloride ion, and uncoordinated methanol/water molecules producing H-bonding stabilized 2D-sheet structures (1, 2, 4), a 1D-single chains (3), and a 3D structure (5). Bulk magnetization measurements on 1–4 demonstrate that the magnetic interactions are completely dominated by an overall ferromagnetic coupling occurring between Ni(II) ions with coupling constants (J1, J2, and J3) ranging from 13.19 to 22.10, (−9.05) to (1.74), and 14.79 to 25.59 cm−1 respectively (in the Ĥ=-2J1(Ŝ1Ŝ3+Ŝ2Ŝ4)-2J2(Ŝ1Ŝ4+Ŝ2Ŝ3)-2J3(Ŝ1Ŝ2)+D(ŜZ12+ŜZ22+ŜZ32+ŜZ42) expression).Figure options