3D network structure and spin gap behavior in two new molecular magnets based on bis(maleonitriledithiolato)nickelate monoanion

Two new molecular magnets, based on [Ni(mnt)2]− monoanion, [DiBrBzPy][Ni(mnt)2] (1) and [DiBrBzIQl][Ni(mnt)2] (2) ([DiBrBzPy]+ = 1-(3′,5′-dibromobenzyl)pyridinium, [DiBrBzIQl]+ = 1-(3′,5′-dibromobenzyl)isoquinolinium and mnt2− = maleonitriledithiolate), were prepared and characterized by elemental analyses, IR, ESI-MS spectra, single crystal X-ray diffraction and magnetic measurements. The [Ni(mnt)2] anions and the cations of 1 and 2 are alternately stacked and form 1D column via π⋯π stacking interactions between the [Ni(mnt)2] anions and the neighboring cations. Some weak Ni⋯N, C⋯N interactions and Csingle bondH⋯Br, Csingle bondH⋯N hydrogen bonds between the adjacent columns further generate a 3D network structure. Magnetic susceptibility measurements show that both 1 and 2 exhibit the typical magnetic behavior of a spin gap system with an energy gap of 1151.9 K for 1 and 73.9 K for 2.