Two molecular metals with one-dimensional non-uniform magnetic chain of bis(maleonitriledithiolate)nickel(III) monoanion: Syntheses, structures and magnetic properties

Abstract

Two new molecular metals, [2FBz-2NH2Py][Ni(mnt)2] (1) and [4FBz-2NH2Py][Ni(mnt)2] (2) ([2FBz-2NH2Py]+=1-(2′-fluobenzyl)-2-aminopyridinium, [4FBz-2NH2Py]+=1-(4′-fluobenzyl)-2-aminopyridinium mnt2−=maleonitriledithiolate), have been prepared and characterized by elemental analyses, IR, MS spectra, single crystal X-ray diffraction. The Ni(III) ions of 1 and 2 form a 1D zigzag non-uniform magnetic chain within a [Ni(mnt)2]− column through Ni⋯Ni, Ni⋯S, Ni⋯C, S⋯C, N⋯C or π⋯π interactions both at 293 and 150K (the crystal structure of 2 at 293K has been briefly reported earlier, here the crystal structure at 150K and magnetic susceptibility are investigated). Upon the temperature is lowered, the non-uniform chain has been compressed with the shortness of Ni⋯Ni distance. Variable temperature magnetic susceptibility measurements agree very well with the 1D non-uniform chain structures, and 1 exhibits a spin-gap transition around 260K with Δ/kB=1160.0K, while 2 shows two spin-gap transitions around 235.7K (Δ/kB=867.8K) and 10.4K (Δ/kB=19.1K), respectively.