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. The terminal chloro/methyl groups are disordered and overlap with an occupancy of 78:22%. The disorder was modelled with restraints (DFIX) and constraints (EADP for the Cl atoms).