Crystal structure and Hirshfeld surface analysis of 1-[(E)-2-(5-chloro-2-hy-droxy-phen-yl)hydrazin-1-yl-idene]naphthalen-2(1H)-one.

The title compound, C16H11ClN2O2, was obtained by diazo-tization of 2-amino-4-chloro-phenol followed by a coupling reaction with β-naphthol. There are two mol-ecules (A and B) in the asymmetric unit. The crystal structure features only one type of inter-molecular inter-action, that is strong hydrogen bonds involving the hydroxyl group. The naphthol and phenol fragments attached to the C=N-N- moiety exhibit an s-trans conformation. In addition, those fragments are almost coplanar, subtending a dihedral angle of 13.11 (2)° in mol-ecule A and 10.35 (2)° in mol-ecule B. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (32.1%), C⋯H/H⋯C (23.1%), Cl⋯H/H⋯Cl (15.2%), O⋯H/H⋯O (12.8%) and C⋯C (9%) contacts.