Trispyrazol-1-ylmethane

In the title compound, C10H10N6, the three N atoms in the 2-positions of the pyrazole rings (the ones not bridging to the central C atom are acceptors for weak C—H⋯N contacts with H⋯N distances ranging from 2.49 to 2.59 Å). These furnish the formation of layers perpendicular to [100]. An orthorhombic polymorph of the title compound has already been described [McLauchlan et al. (2004 ▶). Acta Cryst. E60, o1419–o1420].

In the title compound, C 10 H 10 N 6 , the three N atoms in the 2positions of the pyrazole rings (the ones not bridging to the central C atom are acceptors for weak C-HÁ Á ÁN contacts with HÁ Á ÁN distances ranging from 2.49 to 2.59 Å ). These furnish the formation of layers perpendicular to [100]. An orthorhombic polymorph of the title compound has already been described [McLauchlan et al. (2004). Acta Cryst. E60, o1419-o1420].

Related literature
The compound was prepared according to a published procedure (Reger et al., 2000). For a structure analysis of the orthorhombic polymorph, see: McLauchlan et al. (2004). For classification of hydrogen bonds, see: Bernstein et al. (1995); Etter et al. (1990).
TK thanks the Hanns-Seidel-Stiftung for a PhD scholarship financed by the Bundesministerium fü r Bildung und Forschung.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BT2828).

Comment
The title compound was synthesized as a neutral tridentate ligand for coordination studies with transition metals.
In the molecule, three pyrazole moieties are N-bound to a central C atom (Fig. 1). The molecule is found in a non-symmetric conformation in the solid state. The highest possible symmetry C 3v is broken by the ring containing N4 which is flipped by about 180°.
If only such contacts whose range falls by about 0.2 Å below the sum of van der Waals radii are considered, the crystal structure shows two C-H···N contacts. Infinite strands along [0 1 0] are formed by C6-H6···N2 contacts (Fig. 2). This pattern can be described according to graph-set analysis (Etter et al., 1990;Bernstein et al., 1995) with a C(7) descriptor on the unitary level. In addition, dimeric units are formed by interaction of the H atom of C10 and N6 (Fig. 3). These dimers can be described with a R 2 2 (8) descriptor on the unitary level. Both these described interactions give rise to tubes along [0 1 0].
Considering also contacts whose range falls below the sum of van der Waals radii by only about 0.1 Å, a second dimeric ring system is obvious with a R 2 2 (12) descriptor formed by the H atom of C1 and N4 (Fig. 4). In combination with the interactions described above, this second ring system features the formation of layers perpendicular to [1 0 0] (Fig. 5).
The molecular packing is shown in Figure 6.

Experimental
The compound was prepared according to a published procedure (Reger et al., 2000) upon reaction of pyrazole and chloroform in alkaline aqueous media in the presence of a phase-transfer catalyst (tetrabutylammonium chloride).

Refinement
Carbon-bound H atoms were placed in calculated positions (C-H 1.00 Å for the tertiary C atom and C-H 0.95 Å for aromatic C atoms) and were included in the refinement in the riding model approximation, with U(H) set to 1.2U eq (C).
supplementary materials sup-2 Figures   Fig. 1. The molecular structure of the title compound with atom labels and anisotropic displacement ellipsoids (drawn at 50% probability level) for non-H atoms.