2D crystal structure, magnetic behavior and theoretic analysis of two new molecular solids based on Ni(maleonitriledithiolate)2 monoanion with substituted 2-aminopyridinium

Two new molecular solids, [BzPyNH2][Ni(mnt)2](1) and [2-NpCH2PyNH2][Ni(mnt)2](2) (mnt2− = maleonitriledithiolate, [BzPyNH2]+ = 1-benzyl-2-aminopyridinium and [2-NpCH2PyNH2]+ = 1-(2′-naphthylmethylene)-2-aminopyridinium) have been characterized structurally and magnetically. The Ni(Ш) ions of 1 and 2 form a 1D magnetic chain within a [Ni(mnt)2]− column through Ni⋯N or π⋯π interactions. Some weak interactions observed in 1 and 2 give further rise to a 2D structure. The overlapping fashions of the [Ni(mnt)2]− anions are different when the 2-aminopyridine ring was fixed and the phenyl ring changed into the naphthyl ring of the cation. Magnetic susceptibility measurements in the temperature range 2–300 K show that 1 is weak antiferromagnetic coupling, while 2 exhibits a novel and interesting spin-gap transition around 140 K with Δ/kb = 381.4 K.