1-[(6-Chloropyridin-3-yl)methyl]-10-nitro-1,2,3,5,6,7,8,9-octahydro-5,9-methanoimidazo[1,2-a]azocin-5-ol

In the title compound, C16H19ClN4O3, the cyclohexane ring displays a chair formation and the tetrahydropyridine ring displays an envelope conformation with the methylene C atom as the flap; the imidazolidine ring also displays an envelope conformation with a methylene C atom as the flap. In the crystal, O—H⋯N hydrogen bonds between hydroxy groups and pyridine rings link inversion-related molecules into dimers. Weak C—H⋯O hydrogen bonds further link the dimers into supramolecular chains running along the c axis.

In the title compound, C 16 H 19 ClN 4 O 3 , the cyclohexane ring displays a chair formation and the tetrahydropyridine ring displays an envelope conformation with the methylene C atom as the flap; the imidazolidine ring also displays an envelope conformation with a methylene C atom as the flap. In the crystal, O-HÁ Á ÁN hydrogen bonds between hydroxy groups and pyridine rings link inversion-related molecules into dimers. Weak C-HÁ Á ÁO hydrogen bonds further link the dimers into supramolecular chains running along the c axis.

Shu-Xia Cui, Guang-You Zhang and Zhong-Zhen Tian Comment
The past decades have witnessed the great power and versatile ability of neonicotinoids as a novel class of insecticides (Jeschkel & Nauen, 2008), Several commercial neonicotinoid compounds were launched successively in the latest two decades, and they presented a broad spectrum performance in controlling various insects. Our interest was introducing bicyclic struture to fix the direction of the nitro group, and synthesized a class of novel cis-neonicotinoid compounds with carbon bicyclic, in which the title compound exhibited good insecticidal activities against pea aphids.
The structure of compound is shown in Fig. 1 with the atom-numbering scheme. In the title compound, the the cyclohexane ring displays a chair formation while the hexahydroazocine ring displays an envelope conformation with the methylene C atom on the flap; the imidazolidine ring also displays an envelope confromation with a methylene C atom on the flap. In the crystal, intermolecular O-H···N hydrogen bonds between hydroxyl groups and pyridine rings link inversion-related molecules into dimer. Weak C-H···O hydrogen bonds further link the dimers into the supramolecular arichiecture.

Experimental
The title compound was synthesized according to the literature (Tian et al., 2007). Single crystals suitable for X-ray analysis were obtained by slow evaporation of the solution of dichloromethane and ether of the title compound.

Refinement
Hydroxyl H atom was located in a difference map and refined with distance restraints of O-H = 0.82 Å, U iso (H) = 1.5U eq (O). Other H atoms were positioned geometrically and refined using a riding model with C-H = 0.93-0.98 Å, U iso (H) = 1.2U eq (C).  The molecular structure of the title compound with atom numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. The H atoms are shown as circles of arbitrary size. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.33 e Å −3 Δρ min = −0.34 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. 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 > 2sigma(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.