4,4′-Dichloro-2,2′-[imidazolidine-1,3-diylbis(methylene)]diphenol

The imidazolidine ring in the title compound, C17H18Cl2N2O2, adopts a twist conformation. The observed conformation is stabilized by two intramolecular O—H⋯N hydrogen bonds, with both N atoms acting as hydrogen-bond acceptors. The phenyl substituents are aligned at 70.0 (1) and 76.6 (1)° with respect to the best plane through the five atoms of the imidazolidine ring. Weak intermolecular C—H⋯O interactions stabilize the crystal packing.

The imidazolidine ring in the title compound, C 17 H 18 Cl 2 N 2 O 2 , adopts a twist conformation. The observed conformation is stabilized by two intramolecular O-HÁ Á ÁN hydrogen bonds, with both N atoms acting as hydrogen-bond acceptors. The phenyl substituents are aligned at 70.0 (1) and 76.6 (1) with respect to the best plane through the five atoms of the imidazolidine ring. Weak intermolecular C-HÁ Á ÁO interactions stabilize the crystal packing.
We report here the structure of the title compound (I) (Fig. 1), which was prepared according to the previously reported procedure (Rivera et al., 1993) but using the intriguing aminal 1,3,6,8-tetraazatricyclo[4.3.1.1 3,8 ]undecane. Recrystallization from methanol by slow evaporation over a period of one week affording crystals suitable for X-ray analysis.
The chains, aligned along the c axis, are further linked together via cross-linking weaker C-H···O interactions (Table 1).

Experimental
For the originally reported synthesis, see: Rivera et al. (1993)

Refinement
All H atoms could be located in a difference Fourier synthesis. Nevertheless, H atoms were refined as riding with H bonded to O at the positions where they were found and C-H distances of 0.93 Å for aromatic H and C-H = 0.97Å for methylene groups. All H atoms were refined with displacement coefficients U iso (H) set to 1.5U eq (O) for hydroxyl groups and to 1.2U eq (C) for the CH-and CH 2 -groups. Fig. 1. A view of (I) with the numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.  as those based on F, and R-factors based on ALL data will be even larger. The H atoms were all located in a difference map, but those attached to carbon atoms were repositioned geometrically. The isotropic temperature parameters of hydrogen atoms were calculated as 1.2*U eq of the parent atom. The distance between hydrogen and oxygen atom in hydroxyl group was fixed to the distance 0.87 Å.