The ligating behaviour of 3-hydroxyimino-2-butanone-1-benzoylhydrazone towards NiII and CuII ions

Summary The ligating behaviour of the normally tridentate but potentially tetradentate ligand 3-hydroxyimino-2-butanone-1-benzoylhydrazone (LH₂) towards Cu^II and Ni^II ions has been investigated. The ligand reacts in either its keto or enol form, depending on the pH of the reaction medium. Metal complexes of the type Cu(LH₂)]X₂ · H₂O (X = Cl, NO₃ or ClO₄), Ni(LH₂)₂]X₂ · 2H₂O (X = Cl, Br, NO₃ and ClO₄), Cu(L) and Ni(L) have been isolated and characterised by spectral (u.v-vis., i.r. and e.p.r.) and magnetic susceptibility measurements. Location of the bonding sites and the probable structures of the complexes has also been discussed. The reactions of Cu(L) and Ni(L) with pyridine have also been examined.