Crystal Structure of 1,1′-(1,7-Heptanediyl)bis(pyridinium) Bis(2-thioxo-1,3-dithiole-4,5-dithiolato)nickelate Double Salt

The crystal structure of double salt (1,1'-(1,7-heptanediyl)bis(pyridinium))(2)[Ni(dmit)(2)](3) (dmit = 2-thioxo-1,3-dithiole-4,5-dithiolato) was determined by the single-crystal X-ray diffraction method at 173 K. The title compound crystallizes in the triclinic space group P-1 with a = 9.9562(8)angstrom, b = 12.7874(10)angstrom, c = 15.9682(12)angstrom, alpha = 109.1120(10)degrees , beta = 102.4390(10)degrees , gamma = 102.7060(10)degrees , V = 1780.4(2)angstrom(3) , Dx = 1.741 g/cm(3) , Z = 1. The R1[I > 2 sigma(I)] and wR2 (all data) values are 0.0215 and 0.0580, respectively, for all 5945 independent reflections. The crystal structure contains two types of anions with different valences: [Ni(dmit)(2)](-) (A1) and [Ni(dmit)(2)](2-) (A2). A one-dimensional network was formed between the A1 anions along the a + b axis through pi-pi interactions, and S-S contacts were formed between A1 and A2. The same crystal structure was obtained when the synthetic conditions were changed with the aim of obtaining single salts, thus suggesting that the characteristic double salt was the most stable species.