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

[Ni(bpy)(ox)] (bpy = 2,2-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.