Click the structures and reaction arrows in sequence to view the 3D models and animations respectively
Reaction of carbonyl with hydrazine gives a hydrazone. Hydrazine is more nucleophilic than a regular amine due to the presence of the adjacent nitrogen. Note the similarity to the formation of an oxime reaction. Hydrazones generally form a mixture of geometric isomers.
J. M. Sayer, B. Pinsky, A. Schonbrunn and W. Washtien, J. Am. Chem. Soc., 1974, 96, 7998–8009.