Consolidate the stacking of the molecules The electrostatic interaction between [Ni(i-mnt)2]2– anions and [BzPid]+ cations consolidates the stacking of the molecules. <...> Keywords: bis(iso-maleonitriledithiolate)nickel(II) anion, structure. benzylpiperidinium, crystal With the rapid development of coordination chemistry, studies on transition metal complexes are drawing widespread attention, especially in the field of 1,2-dithiolene ligands, due to their highly electronic extend systems, excellent properties and application in the conductive, superconductive and magnetic properties [ 1—8]. <...> In addition, more and more relevant reports and researches have proven that a typical complex anion of the 1,2-dithiolene ligand [M(mnt)2]n– (M = Ni, Pd, Pt, Cu; n = 1 or 2; mnt = maleonitriledithiolate) is a useful building block to find some molecular materials with unusual magnetic properties [ 7, 9—12 ]. <...> In fact, the planar geometry of i-mnt complexes also enables them to increase their coordination numbers by binding to molecules such as thiazole derivatives [ 13, 14 ]. <...> The crystal structure, weak interactions and the stacking mode of 1 have systematically been investigated. <...> Benzyl bromide, piperidine, nickel(II) chloride hexahydrate and solvents were purchased from commercial sources and used as received. 1-[Benzylpiperidium] bromide (BzPidBr) and disodium iso-maleonitriledithiolate (K2(i-mnt)H2O) were synthesized following the literature procedures [ 20, 21 ]. [BzPid]2[Ni(i-mnt)2] (1) was prepared by the direct combination of NiCl26H2O, K2(i-mnt)H2O, and [BzPid]Br in the 1:2:2 molar ratio. <...> Microanalyses for C, H and N were obtained from a Perkin Elmer 240C CHN elemental analyser. <...> IR spectra (4000— 400 cm–1) were recorded with an IF66V FT—IR spectrophotometer using KBr pellets. <...> Electrospray mass spectra (ESI-MS) were determined on a Finnigan LCQ mass spectrograph and the sample con© Hu Y.-L., Liang L.-B., Liu J.-F., Chen W.-Q., Zhou J.-R., Liu X.-P., Yang L.-M., Ni C.-L., 2013 . 755 – 758 756 Table 1 Main crystallographic parameters and running characteristics <...>