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. Hydrogen atoms H2, H3 and H4 were found from a difference-Fourier map and were refined isotropically, using DFIX restraints with O–H distances of 0.90 (1) Å. Isotropic displacement parameters were set to 1.2 Ueq of the parent nitrogen atom and 1.5 Ueq of the parent oxygen atom. All other hydrogen atoms were placed in calculated positions with C–H = 0.93 Å (sp2) or 0.97 Å (sp3). Isotropic displacement parameters were set to 1.2 Ueq of the parent carbon atom.