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Syntheses, Structures, and Magnetic Properties of a Novel mer-[(bbp)FeIII(CN)3]2– Building Block (bbp: bis(2-benzimidazolyl)pyridine dianion) and Its Related Heterobimetallic Fe(III)–Ni(II) Complexes

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journal contribution
posted on 19.11.2012, 00:00 authored by Anangamohan Panja, Philippe Guionneau, Ie-Rang Jeon, Stephen M. Holmes, Rodolphe Clérac, Corine Mathonière
A new symmetrical tricyanide building block mer-[Fe­(bbp)­(CN)3]2– [1; bbp = bis­(2-benzimidazolyl)­pyridine dianion] has been prepared and structurally and magnetically characterized. It forms a new low-spin meridionally capped {FeIIIL­(CN)3} fragment with the tridentate bbp ligand. The reaction of 1 with NiII salts in the presence of various ancillary ligands affords several new cyanido-bridged complexes: a trinuclear complex {[Ni­(ntb)­(MeOH)]2[Fe­(bbp)­(CN)3]­[ClO4]2}·2MeOH (2), a tetranuclear compound {[Ni­(tren)]2[Fe­(bbp)­(CN)3]2}·7MeOH (3), and a one-dimensional heterobimetallic system: {[Ni­(dpd)2]2[Fe­(bbp)­(CN)3]2}·9MeOH·3H2O (4) [ntb = tris­(2-benzimidazolylmethyl)­amine, tren = tris­(2-aminoethyl)­amine, and dpd = 2,2-dimethyl-1,3-propanediamine]. The structural data shows that 2 is a linear complex in which a central FeIII ion links two adjacent NiII ions via axial cyanides, while 3 is a molecular square that contains cyanido-bridged NiII and FeIII ions at alternate corners. Complex 4 is a one-dimensional system that is composed of alternating cyanido-bridged NiII and FeIII centers. Compounds 24 display extensive hydrogen bonding and moderately strong π–π stacking interactions in the solid state. Magnetic studies show that ferromagnetic exchange is operative within the FeIIILS(μ-CN)­NiII units of 24.

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