Related Experiment Video
Updated: Apr 30, 2026
![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
A second polymorph of (Z)-3-amino-4-(2-phenyl-hydrazinyl-idene)-1H-pyrazol-5(4H)-one
Abdel-Sattar S Hamad Elgazwy1, Peter G Jones2
1Chemistry Department, Faculty of Science, Ain Shams University, Abbassia 11566, Cairo, Egypt.
Abstract:
The mol-ecule of the title compound, C9H9N5O, is approximately planar (the r.m.s. deviation of all non-H atoms is 0.08 Å). The amine substituent is pyramidal at the N atom. An intra-molecular N-Hhydrazine⋯O=C hydrogen bond is present. In the crystal, mol-ecules are connected via N-H⋯N and N-H⋯O hydrogen bonds, forming infinite layers parallel to (010). This polymorph is triclinic, space group P-1, whereas the previously reported form was monoclinic, space group P21/c [Elgemeie et al. (2013 ▶). Acta Cryst. E69, o187], with stepped layers and a significantly lower density.
Related Concept Videos
Diazonium Group Substitution: –OH and –H
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
Nomenclature of Aryl and Heterocyclic Amines
Five-Membered Heterocyclic Aromatic Compounds: Overview
Basicity of Heterocyclic Aromatic Amines
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo,...

