Syntheses and crystal structures of benzyl N⁰-[(E)-2hydroxybenzylidene]hydrazinecarboxylate and benzyl N⁰-[(E)-5-bromo-2-hydroxybenzylidene]hydrazinecarboxylate

Benzyl N⁰-[(E)-2-hydroxybenzylidene]hydrazinecarboxylate, C₁₅H₁₄N₂O₃ (I) and benzyl N⁰-[(E)-5-bromo-2-hydroxybenzylidene]hydrazinecarboxylate (II), C₁₅H₁₃BrN₂O₃, have been synthesized by the reaction of either 2-hydroxy-benzaldehyde or 5-bromo-2-hydroxybenzaldehyde with benzyl carbazate, respectively. Both the compounds crystallize in the monoclinic crystal system with space groups Pn (Z⁰ = 1, I) and P2₁/c (Z⁰ = 2, II). Molecular conformations in each structure are similar, and both structures feature strong intramolecular O—H. . .N hydrogen bonds, which form S(6) ring motifs. There are also strong N—H. . .O and weak C—H. . .O hydrogen bonds in both structures, but their modes of packing within their respective crystals are markedly different. Some comparisons are made with the structures of a few related compounds.