[Ni(bpy)(ox)]: a candidate in the class of Haldane gap systems (bpy = 2,2ʹ-bipyridine, ox = oxalate)

Abstract

To cite this article: J. Černák, N. Farkašová, M. Tomás, V. Kavečanský, E. Čižmár & M. Orendáč (2015): [Ni(bpy)(ox)]: a candidate in the class of Haldane gap systems (bpy = 2,2ʹ-bipyridine, ox = oxalate), Journal of Coordination Chemistry,[Ni(bpy)(ox)] (bpy = 2,2ʹ-bipyridine; ox = oxalate) was solvothermally prepared in the microcrystalline form and identified by chemical analyses and IR spectroscopy. X-ray powder diffractometry indicates its isostructural character with analogous complexes [M(bpy)(ox)], and thus, its chain-like crystal structure formed of {Ni(bpy)} building units linked by bridging oxalate anions coordinated in a bis(chelate) fashion. The temperature dependence of the magnetic susceptibility and the field dependence of the magnetization reveal that the studied compound belongs to the class of systems with a Haldane gap. The estimated magnitude of the gap E g ≈ 13.4 cm −1 is comparable with those found in archetypal Haldane gap systems.

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“…The patterns recorded in Figure a and Figures S40–S43 show that different compositions of ligands give rise to various crystal phases depending on the coordination behaviors of transitional metals. However, there is a mutual crystal structure (Figure a and Table S8) recognized for four MBO precursors as ZnBO, which have an orthorhombic phase with the space group as Pna 2 1 and point group as mm 2, disclosed by the simulation analysis . The corresponding molecular structure, which is regarded as a secondary building unit, is also described as a transition metal coordinated with one 2,2′-bipyridine group via two N atoms and two oxalate groups via four O atoms.…”

“…However, there is a mutual crystal structure (Figure 7a and Table S8) recognized for four MBO precursors as ZnBO, which have an orthorhombic phase with the space group as Pna2 1 and point group as mm2, disclosed by the simulation analysis. 73 The corresponding molecular structure, which is regarded as a secondary building unit, is also described as a transition metal coordinated with one 2,2′-bipyridine group via two N atoms and two oxalate groups via four O atoms. That is to say, the comparison above suggests the MBO analogues have a similar structure albeit with different metals.…”

Haldane topological spin-1 chains in a planar metal-organic framework

“…Properties of 1D Haldane spin-1 materials have been probed experimentally using, e.g., Ni 2+ -based chains bridged by NO 2 − , N 3 − , ox 2− , or HF 2 − ligands 3 , such as [Ni(en) 2 ( μ -NO 2 )](ClO 4 ) (NENP; en = ethylenediamine) 15 – 20 , [Ni(1,3-propanediamine) 2 ( μ -NO 2 )](ClO 4 ) (NINO) 20 , 21 , [Ni(en) 2 ( μ -NO 2 )](BF 4 ) (NENB) 22 – 24 , [Ni(dmpn) 2 ( μ -N 3 )](ClO 4 ) (NDMAZ; dmpn = 1,3-diamino-2,2-dimethylpropane) 25 , [Ni(3,2,3-tet)( μ -N 3 )](ClO 4 ) [232-tet = bis(2-aminoethyl)-l,3-propanediamine] 26 , [Ni(2,2′-bpy)( μ -ox)] n (bpy = bipyridine) 27 , [Ni(benzimidazole) 2 ( μ -ox)] n 28 , and [NiI 2 (3,5-lut) 4 ] n (3,5-lut = 3,5-lutidine) 29 . In the 1D chains with mono-anionic μ -NO 2 − or μ -N 3 − ligands bridging Ni 2+ ions such as NENP or NENB, the Haldane chains carry + charges, requiring anions ClO 4 − or BF 4 − to balance the charges.…”

“…In [Ni(HF) 2 (pyz) 2 ]SbF 6 30 , the mono-anionic HF 2 − ligands also form cationic 1D linear chains along the c axis in the coordination polymer, using the SbF 6 − anions to balance the + charges. In [Ni(2,2′-bpy)( μ -ox)] n 27 [Ni(benzimidazole) 2 ( μ -ox)] n 28 , the N-ligands, 2,2′-bpy or benzimidazole, are cis -coordinated to Ni 2+ ions, forming zig-zag structures.…”