1-(4-Cyanobenzyl)-3,5-dimethylpyridinium bis(benzene-1,2-dithiolato)nickelate(III)

The asymmetric unit of the title compound, (C15H15N2)[Ni(C6H4S2)2], contains half each of two independent centrosymmetric anions and a single cation in a general position. The NiIII ions are coordinated by four S atoms in a square-planar geometry. The anions exhibit two packing modes, viz. stacked along the a axis in a face-to-face fashion with an alternate arrangement of anions and cations, and stacked in a side-by-side fashion, forming ribbons parallel to (011).

The asymmetric unit of the title compound, (C 15 H 15 N 2 )-[Ni(C 6 H 4 S 2 ) 2 ], contains half each of two independent centrosymmetric anions and a single cation in a general position. The Ni III ions are coordinated by four S atoms in a square-planar geometry. The anions exhibit two packing modes, viz. stacked along the a axis in a face-to-face fashion with an alternate arrangement of anions and cations, and stacked in a side-by-side fashion, forming ribbons parallel to (011).

Related literature
For general background to molecular-based magnetic materials, see: Jones (1997); Akutagawa et al. (2009). For the role played by the size and shape of the counter-cations in determining the ground-state properties of the resulting materials, see: Ren et al. (2003). For related structures, see: Sellmann et al. (1991); Xie et al. (2002Xie et al. ( , 2003; Ren et al. (2002).

Experimental
Crystal data (C 15

Comment
Molecular solids with particular functionality are continuously paid much attention by chemists and physicists in the field of materials science (Jones, 1997). The preparation of new molecular based spin-bearing systems, among others, has been pursued from the viewpoint of materials/physical organic chemistry to develop novel molecular-based magnetic materials (Akutagawa et al., 2009). In our previous research using benzylpyridinium derivatives ([RBzPy] + ) as the counter-cation of [M(mnt) 2 ] -(where M = Ni, Pd and Pt and mnt 2-= maleodinitriledithiolate), a series of ion-pair compounds with segregated columnar stacks of cations and anions has been prepared (Ren et al., 2002;Ren et al., 2003;Xie et al., 2002). The quasi one-dimensional magnetic nature of these compounds was attributed to intermolecular orbital interactions within the anionic columns. As an extension of our work on this series of complexes, we report here the crystal structure of the title compound, (I).
The asymmetric unit of (I) contains half each of two independent centrosymmetric [Ni(C 6 H 4 S 2 ) 2 ]anions and one (C 15 H 15 N 2 ) + cation. In the anions, the nickel(III) ions are coordinated by four S atoms in a square-planar geometry; the Ni-S bonds and S-Ni-S angles are in agreement with the corresponding values found in analogous complexes (Sellmann et al., 1991;Xie et al., 2003). The centrosymmetric [Ni(C 6 H 4 S 2 ) 2 ]anions are almost planar. The dihedral angle between the two benzene rings of the cation is 86.49 (6)°. In the crystal structure, the packing of the two anions is different (Fig. 2).
The Ni1-containing anions stack in a side-by-side fashion, forming one-dimensional ribbons parallel to (011); the shortest distance between the adjacent nickel(III) ions is 7.152 (6) Å. The Ni2-containing anions stack in a face-to-face fashion along the a axis with an alternating arrangement of [Ni(C 6 H 4 S 2 ) 2 ]anions and [C 15 H 15 N 2 ] + cations such that the pyridine ring of the cation lies above the benzene ring of the anion. The shortest distance between adjacent nickel(III) ions is also 7.152 (6) Å. A Ni···Ni distance of 8.155 (9)Å is found between adjacent Ni1-containing and Ni2-containing anions.

Experimental
Benzene-1,2-dithiol (142 mg, 1.0 mmol) was added to a solution of sodium metal (46 mg, 2.0 mmol) in absolute ethanol (25 ml), under a nitrogen atmosphere at room temperature. A solution of NiCl 2 .6H 2 O (120 mg, 0.5 mmol) in ethanol (25 ml) was added, resulting in the mixture turning a muddy red-brown colour. Following this, [CNBzPy(CH 3 ) 2 ]Br (304 mg, 1.0 mmol) was added and the mixture allowed to stand with stirring for 1 h, and then stirred for an additional 24 h in air. The colour of the mixture gradually turned green, indicating oxidation from a dianionic species to the more stable monoanionic form. The precipitate was washed with absolute ethanol and diethyl ether and then dried. The crude product was recrystallized twice from dichloromethane to give the title compound (yield 198 mg, 54%).