Insight into weakly antiferromagnetic coupling behavior in a non-integer oxidation state bis(2-thioxo-1,3-dithiole-4,5-dithiolate)nickelate molecular semiconductor

In this study, we prepared a salt, (ImH)[Ni(dmit)2]2 (1; ImH+= imidazolium; dmit2-= 2-thioxo-1, 3-dithiole-4, 5-dithiolate), by a facile approach of chemical oxidation together with solvent evaporation at ambient condition. (1) was characterized by microanalysis for C, H and N elements, IR spectroscopy, TG and DSC techniques. 1 crystallizes in triclinic space group P -1, with two different [Ni(dmit)2] species (Ni1 and Ni2) and one ImH+ cation in an asymmetric unit. The characteristic C--C, C-S and Ni-S bond lengths in [Ni(dmit)2] species demonstrated that the valences of two different [Ni(dmit)2] species are-0.5. The anions form dimeric stacks in 1, which are further connected into monolayers by inter-stack S...S interactions. 1 shows semiconducting feature with sigma DC = 1.45 x 10-3 S cm -1 at 293 K and Ea = 0.17 eV; and smaller Weiss constant (-0.67 K) owing to the magnetic couplings being achieved through weak dipole-dipole interactions.