Dichlorido[2-(3,5-dimethyl-1H-pyrazol-1-yl-κN 2)ethanamine-κN]zinc(II)

The amine title complex, [ZnCl2(C7H13N3)], resulted from imine hydrolysis in a Schiff base compound. The Zn metal atom has a distorted tetrahedral geometry with the most significant deviation identified in the magnitude of the N—Zn—N angle. This deviation stems from the participation of the Zn and N atoms in a six-membered metallocyclic ring. The latter is in an approximate screw-boat conformation. Two strong N—H⋯Cl hydrogen bonds link the molecules into ribbons propagating along the b-axis direction. The ribbons contain two second-order hydrogen-bonded motifs: a chain and a ring. The chain described by the graph set notation C 2 2(6) is formed by one hydrogen bond going in the forward direction (donor to acceptor) and the other in the backward direction (acceptor to donor). In the ring motif R 2 2(8), both hydrogen bonds propagate in the forward direction.

The amine title complex, [ZnCl 2 (C 7 H 13 N 3 )], resulted from imine hydrolysis in a Schiff base compound. The Zn metal atom has a distorted tetrahedral geometry with the most significant deviation identified in the magnitude of the N-Zn-N angle. This deviation stems from the participation of the Zn and N atoms in a six-membered metallocyclic ring. The latter is in an approximate screw-boat conformation. Two strong N-HÁ Á ÁCl hydrogen bonds link the molecules into ribbons propagating along the b-axis direction. The ribbons contain two second-order hydrogen-bonded motifs: a chain and a ring. The chain described by the graph set notation C 2 2 (6) is formed by one hydrogen bond going in the forward direction (donor to acceptor) and the other in the backward direction (acceptor to donor). In the ring motif R 2 2 (8), both hydrogen bonds propagate in the forward direction.

Comment
Imine hydrolysis in Schiff base compounds is quite common. It is usually driven by traces of water and the presence of acidic metal ions, especially in the case of the first row transition metal chlorides such as Co II , Ni II (Czaun et al., 2010) and Cu II (Bu et al., 1997;Czaun et al., 2010;Koner & Ray, 2008;Sinha et al., 2003). In a recent attempt to prepare a Zn II complex from the reaction of 2-{[2-(3,5-dimethylpyrazol-1-yl)ethylimino]}-4,6-ditertbutylphenol with zinc(II) chloride, we isolated the title compound (I), a hydrolysis product of the imine to an amine.
The complexes may contain metallocyclic rings with five, six, seven, eight, ten, thirteen, or sixteen atoms as well as no  (Bruno et al., 2002).
Two strong intermolecular hydrogen bonding interactions N3-H3b···Cl1 [-x + 3/2, y + 1/2, -z + 1/2] (a) and N3-H3a···Cl2 [-x + 3/2, y -1/2, -z + 1/2] (b) link molecules of (I) in chains parallel to the b axis. The chains form an motif (the arrows above the bond designators show the direction of the bond; the forward arrow corresponds to the donor-to-acceptor direction whereas the backward arrow to the acceptor-to-donor direction) described by the second order graph set notation C 2 2 (6) (Bernstein et al. 1995). The hydrogen bonds also form an ring motif described by the second order graph set notation R 2 2 (8) with both bonds in the forward direction.

Refinement
All H-atoms attached to carbon atoms were placed in idealized locations and refined as riding with appropriate thermal displacement coefficients U iso (H) = 1.5 times U eq (bearing atom) for H atoms attached to nitrogen atoms and U iso (H) = 1.2 times U eq (bearing atom) for all other H atoms. Default effective X-H distances for T = -173.0° C C(sp 3)-2H=0.99, C(sp 3)-3H=0.98, C(sp 2)-H=0.95, N-2H=0.92 Å. Fig. 1. Molecular structure of (I). The thermal ellipsoids are shown at 50% probability level.

Dichlorido[2-(3,5-dimethyl-1H-pyrazol-1-yl-κN 2 )ethanamine-κN]zinc(II)
Crystal data [ZnCl 2 (C 7  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 Rfactors(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.