Crystal structures, magnetic and electrical properties of two new two-dimensional bis(2-thioxo-1, 3-dithiole-4, 5-dithiolato)nickelate salts

• Two isostructural nickel-bis(2-thioxo-1,3-dithiole-4,5-dithiolato) salts show alternating anions and cations layered structure.
• There are novel H-bonds of charge-assisted S⋯H between anions and cations layers.
• The strong antiferromagnetic coupling occurs between the face-to-face stacked anions within an anion layer.
• Two salts show thermal-activated dipolar motion and dielectric relaxation above 175 K.

Two new salts of bis(2-thioxo-1, 3-dithiole-4, 5-dithiolato) nickelate monoanion with 4-amino-1-heptylpyridinium (1) and 4-amino-1-nonylpyridinium (2) were prepared and characterized. Two isostructural salts with anion/cation = 1:1 crystallize in space group P-1 with similar cell parameters and packing structures. The anions and cations form alternating layered arrangements, which are connected via charge-assisted S⋯H H-bonds. Within an anion layered alignment, the magnetic exchange is transmitted between the neighboring anions via three types of pathways (face-to-face π–π stack, lateral-to-lateral and head-to-tail S⋯S contacts), where the stronger antiferromagnetic coupling occurs between the face-to-face stacked anions, owing to π-type magnetic orbitals efficiently overlapped, than others and dominates the magnetic nature of 1 and 2. The dielectric and conducting properties were also investigated for two salts in the temperature range of 175–375 K.

Two isostructural [Ni(dmit)2]− salts show strong antiferromagnetic interaction within the [Ni(dmit)2]22− π-dimer and thermal-activated dipolar motion and dielectric relaxation above 175 K.Figure optionsDownload as PowerPoint slide