Two new ion-pair complexes containing derivatives of substituted benzyl isoquinolinium and bis(maleonitriledithiolato)nickelate monoanion: 3D crystal structures, magnetic properties and theoretical analyses

Syntheses, structural characterizations, magnetic behaviors and theoretical analyses of two new ion-pair complexes, [IFBzIQl][Ni(mnt)2](1) and [IClBzIQl]2[Ni(mnt)2]2 · MeCN(2) [IFBzIQl][Ni(mnt)2] ([IFBzIQl]+ = 1-(2′-fluoro-4′-iodobenzyl)isoquinolinium, [IClBzIQl]+ = 1-(2′-chloro-4′-iodobenzyl)isoquinolinium, mnt2− = maleonitriledithiolate), have been investigated. In crystal of 1, the [Ni(mnt)2]− anions and the [IFBzIQl]+ cations stack into an alternating column through π⋯π stacking interactions. The anions of both 1 and 2 form a dimer via π⋯π stacking and S⋯S short interactions between the [Ni(mnt)2]− anions. The overlapping mode of two neighboring [Ni(mnt)2]− anions in the dimer is the Ni-ring fashion with a Ni⋯Ni distance of 4.076 Å for 1, and ring–ring fashion with the Ni⋯Ni and S⋯S distances being 4.395 and 3.593 Å for 2. Some weak interactions such as π⋯π, C⋯N, C–H⋯F or C–H⋯N in 1 and 2 play a crucial role in stacking and stabilizing the crystal lattice, and give a 3D network structure and exchange pathways of the magnetic interaction for 1 and 2. Magnetic susceptibility measurements for 1 and 2 in the temperature range 1.8–300 K show that the overall magnetic behavior indicates the presence of antiferromagnetic interaction, while 2 exhibits an activated magnetic behavior in the high-temperature region (HT) together with a Curie tail in the low-temperature region (LT).