Chelate linkage isomers of (3-Hydroxyimino-4,9-dimethyl-5, 8-diazadodeca-4,9-diene-2,11-dionato) nickel(II)

Isomers of the named compound and their 15N- and 18O-labelled analogues were analysed by p.m.r., infrared, and mass spectrometry. Evidence indicates that the isomers differ only in the mode of attachment of the oxime group of the ligand to the nickel atom in each molecule. Significant differences in carbonyl frequencies have been noted for the uncoordinated acetyl groups attached to the five- and six-membered chelate rings.