Cyclohexane-1-spiro-2′-imidazolidine-5′-spiro-1′′-cyclohexan-4′-one

In the title compound, C13H22N2O, the central imidazolidine ring is in an envelope conformation and the two cyclohexane rings adopt chair conformations. In the crystal structure, the molecules are linked into centrosymmetric R 2 2(8) dimers by pairs of N—H⋯O hydrogen bonds.

In the title compound, C 13 H 22 N 2 O, the central imidazolidine ring is in an envelope conformation and the two cyclohexane rings adopt chair conformations. In the crystal structure, the molecules are linked into centrosymmetric R 2 2 (8) dimers by pairs of N-HÁ Á ÁO hydrogen bonds.

Comment
Imidazolidines occupy a unique position among the five-membered heterocycles and are highly used in synthetic as well as mechanistic organic chemistry and biochemistry (Tsao et al., 1991). Imidazolidine derivatives are important intermediates and building blocks in the construction of various biologically active compounds (Wang et al., 1995).
Evaporation of ether yielded the title compound which was recrystallized by slow evaporation of a water-acetone (20:2) solution.

Refinement
N-bound H atoms were located in a difference map and refined freely. C-bound H atoms were positioned geometrically (C-H = 0.97 Å) and allowed to ride on their parent atoms, with U iso (H) = 1.2U eq (C).

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 > 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.