3,5,3′,5′-Tetramethyl-4,4′-bi(1H-pyrazolyl) hemihydrate

In the title compound, C10H14N4·0.5H2O, the amino H atom of one of the two pyrazole rings is disordered over its two N atoms in a 1:1 ratio. The pyrazole rings are aligned at 60.1 (1)°. In the crystal, two bipyrazolyl molecules are linked by an N—H⋯N hydrogen bond, generating a dimer; the dimer is connected to the water molecule, which lies on a twofold rotation axis, resulting in the formation of a chain that makes an angle of ca 45.3 (1)° with the ab plane. The chains are cross-linked by N—H⋯O and O—H⋯N interactions, forming a three-dimensional network.

In the title compound, C 10 H 14 N 4 Á0.5H 2 O, the amino H atom of one of the two pyrazole rings is disordered over its two N atoms in a 1:1 ratio. The pyrazole rings are aligned at 60.1 (1) . In the crystal, two bipyrazolyl molecules are linked by an N-HÁ Á ÁN hydrogen bond, generating a dimer; the dimer is connected to the water molecule, which lies on a twofold rotation axis, resulting in the formation of a chain that makes an angle of ca 45.3 (1) with the ab plane. The chains are crosslinked by N-HÁ Á ÁO and O-HÁ Á ÁN interactions, forming a three-dimensional network.
We gratefully acknowledge the financial support of the Education Office Foundation of Zhejiang Province (project No. Y201017321)  The use of 3,5,3′,5′-tetramethyl-1H,1′H-[4,4′]bipyrazolyl has drawn strong interest in coordination chemistry (Zhang et al., 2008, Boldog et al., 2001. In the crystal structure of C 10 H 14 N 4 . 0.5H 2 O, the amino H atom of one of the two pyrazole rings is disordered over its two N atoms in a 1:1 ratio. The two pyrazole rings are aligned at 60.1 (1)°. Two C 10 H 14 N 4 molecules are linked by an N-H···N hydrogen bond to generate a dimer; the dimer is connected to the water molecule, which lies on a twofold rotation axis to chain that makes an angle of ca 45.3 (1)° with the ab plane. The chains were crosslinked together by N-H···O, and O-H···N associations to form a three-dimensional network structure Experimental 3,5,3′,5′-Tetramethyl-1H,1′H-[4,4′]bipyrazolyl was prepared according to the literature and crystals were grown from its solution in ethanol. (Boldog et al. 2001).

Refinement
H atoms bonded to N, and O atoms were located in a difference Fourier map and refined isotropically.
Other H atoms were positioned geometrically with C-H = 0.96 Å, and constrained to ride on their parent atoms with U iso (H) = 1.2Ueq(C).

Figure 2
The chain structure formed through the nonbonding interactions. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.