Comment

A great deal of work has been reported on the synthesis and characterization of different types of bis(dithiolato)metal complexes. The studies of these bis(dithiolato)metal compounds have been extended to other properties and uses, such as conducting Langmuir-Blodgett films, unconventional magnetic properties and non-linear optics. Since the first molecular superconductor containing a transition metal complex, (TTF)[M(dmit)₂]₂ (M = Ni or Pd, TTF is tetrathiafulvalene and dmit^2- is 2-thioxo-1,3-dithiole-4,5-dithiolate), was found by Brossard et al. (1986, 1989), extensive studies have been carried out on the assembled metal complexes of dmit and related compounds. The magnetic properties of substituted benzylpyridiniums have been studied in recent years, and several interesting magnetic properties, such as ferromagnetism, weak ferromagnetism, antiferromagnetism, weak antiferromagnetism and spin Peierls transitions have been found (Xie, Ren, Gao et al., 2002; Xie, Ren, Song et al., 2002; Ren et al., 2001). In the present work, we have prepared the title salt [N-(4-NO₂-benzyl)-1-CH₃-py][Ni(dmit)₂], (I), and determined its crystal structure.

The salt (I) has ions in a ratio of 1:1, as expected from the results of elemental analysis. The ratio of 1:1 proves that the oxidation state of nickel is +3. The coordination around the nickel ion is approximately planar (Fig. 1). The deviation of Ni1 from the Ni1/S1/S5/S6/S10 plane is 0.0089 (8) Å. The pyridine ring is approximately parallel to the Ni(dmit)₂ plane [9.17 (17)°]. The dihedral angle between the phenyl and pyridine rings is 67.14 (13)°. There are two poles, composed of anions and cations, in the structure. Anions are grouped by weak NiS [3.694 (2) Å] and SS [range 3.640 (2)-3.781 (2) Å] interactions. These groups, together with the cations, form layers through non-classical hydrogen bonds [3.489 (6) Å]. The SS, NiS and non-classical hydrogen bonds link the molecules into quasi-three-dimensional layers (viz. the layers are finite), which stack to form the crystal structure (Fig. 2 and Fig. 3).

In another salt, [N-(4-Br-benzyl)-py][Ni(dmit)₂], (II), reported in our previous work (Tong et al., 2002), the deviation of Ni^III from the Ni1/S1/S5/S6/S10 plane was 0.008 (7) Å. The pyridine ring was approximately parallel to the Ni(dmit)₂ plane [10.17 (18)°]. The dihedral angle between phenyl and pyridine rings was 81.30 (13)°. Some non-classical hydrogen bonds (C-HS) were found [range 3.557 (5)-3.772 (5) Å]. The anions composed double-deck layers. In these layers, there were some weak NiNi [3.5063 (9) Å] and SS [3.4897 (17)-3.7625 (18) Å] interactions between layers and weak SS [3.5840 (16)-3.7015 (15) Å] interactions between different ions in the same layer. The NiNi, SS and non-classical hydrogen bonds link the molecules into a three-dimensional framework. Thus, the coordination around the nickel is approximately planar in both salts.

Figure 1 View of the asymmetric unit of (I), showing 50% displacement ellipsoids for non-H atoms.

Figure 2 A view of the packing of (I), viewed along the b axis.

Figure 3 The packing of (I); weak interactions are indicated by dashed lines.

Experimental

A solution of NaOMe dissolved in methanol was added to a methanol solution of 4,5-bis(benzoylthio)-1,3-dithiol-2-thione, dmit(COPh)₂. After stirring, a solution of NiCl₂.6H₂O was added. After further stirring, a solution of [N-(4-NO₂-benzyl)-1-CH₃-pyridine]Cl was added. The black precipitate was dissolved in acetone. As the solvent slowly evaporated, well-formed crystals of (I) appeared.