Benzyl N-((S)-2-hydroxy-1-{N′-[(E)-2-methoxybenzylidene]hydrazinecarbonyl}ethyl)carbamate from synchrotron data

A U-shaped conformation is found in the title compound, C19H21N3O5, with the benzene rings lying to the same side of the molecule; the dihedral angle between them is 10.83 (16)°. The dihedral angle formed between the hydrazinecarbonyl and carbamate residues is 68.42 (13)°. The carbonyl groups lie approximately at right angles to each other [O—C⋯C—O pseudo torsion angle of 107.7 (3)°], and the conformation about the C12=N3 bond [1.279 (4) Å] is E. An intramolecular Ncb—H⋯Ohy (cb = carbmate and hy = hydroxy) hydrogen bond occurs, generating an S(6) loop. In the crystal, intermolecular Oh—H⋯Oca (ca = carbonyl) and Nhz—H⋯Oca (hz = hydrazine) hydrogen bonds lead to the formation of a supramolecular chain, two molecules thick, which propagates along the a axis; these are connected by C—H⋯Oca contacts.

A U-shaped conformation is found in the title compound, C 19 H 21 N 3 O 5 , with the benzene rings lying to the same side of the molecule; the dihedral angle between them is 10.83 (16) . The dihedral angle formed between the hydrazinecarbonyl and carbamate residues is 68.42 (13) . The carbonyl groups lie approximately at right angles to each other [O-CÁ Á ÁC-O pseudo torsion angle of 107.7 (3) ], and the conformation about the C12 N3 bond [1.279 (4) Å ] is E. An intramolecular N cb -HÁ Á ÁO hy (cb = carbmate and hy = hydroxy) hydrogen bond occurs, generating an S(6) loop. In the crystal, intermolecular O h -HÁ Á ÁO ca (ca = carbonyl) and N hz -HÁ Á ÁO ca (hz = hydrazine) hydrogen bonds lead to the formation of a supramolecular chain, two molecules thick, which propagates along the a axis; these are connected by C-HÁ Á ÁO ca contacts.
Whereas the carbamate-N1-H atom forms an intramolecular N-H···O hydrogen bond to the hydroxyl-O3 atom, the hydroxyl-O3-H atom forms an intermolecular O-H···O interaction with the carbonyl-O4 atom, and the hydrazine-N2-H atom likewise forms an N-H···O hydrogen bond with the carbonyl-O2 atom. The intermolecular hydrogen bonds lead to the formation of a supramolecular double-chain along the a direction, Fig. 2, with additional stability to the chain afforded by C-H···O interactions involving the carbonyl-O2 atom, Table 1. The primary interactions between chains are of the type C-H···O and involve the carbonyl-O4 atom, Table 1 and Fig. 3.
Solution NMR spectra revealed the presence of (E)-and (Z)-isomers, however, the colourless needles of (I) obtained from MeOH solution were solely the (E)-isomer, m.pt. 453-454 K.

Refinement
The C-bound H atoms were geometrically placed (C-H = 0.95-1.00 Å) and refined as riding with U iso (H) = 1.2-1.5U eq (parent atom). The O-and N-bound H atoms were refined with the distance restraints 0.84±0.01 and 0.88±0.01 Å, respectively. In the absence of significant anomalous scattering effects, 1278 Friedel pairs were averaged in the final refinement. Fig. 1. The molecular structure of (I) showing displacement ellipsoids at the 50% probability level.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s 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 > 2σ(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.  (5) 104 (2)