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. H atoms were positioned geometrically and refined as riding: C–H = 0.95–0.98 Å with Uiso(H) = 1.5Ueq(C) for methyl H atoms and = 1.2Ueq(C) for other H atoms. Amine H atoms were refined isotropically. The absolute structure could not be determined in the present refinement.