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 hydrazide H2, H3A, and H3B atoms were located in difference-Fourier maps while all other hydrogen atoms were initially placed in calculated positions with their coordinates constrained to ride on their carrier atoms [C—H(aromatic) = 0.95?Å, C—H(methyl) = 0.98?Å]. The constraint Uiso(H) = 1.2Ueq(carrier) or 1.5Ueq(methyl carrier) was applied in all cases.