Kinetics and thermodynamics of fast square-planar–octahedral inter-conversion. Part 3. The reaction of [biacetyl bis-α-hydroxybenzyl-idenehydrazone(2–)-N1N1′OO′] nickel(II) with bidentate heterocyclic amines in chlorobenzene
The square-planar complex [Ni(bbh)][bbh = biacetyl bis-α-hydroxybenzylidenehydrazone (2–)-N1N1′OO′] reacts with 2,2′-bipyridine and substituted 1,10-phenanthrolines to give octahedral adducts in which, presumably, the ligand bbh behaves as a tridentate ligand and a hydroxy-group of the water present in the solvent occupies one of the positions around the nickel atom. A comparative thermodynamic and kinetic study of these reactions has been made. The mechanism proposed implies a nickel-to-oxygen bond breaking as the rate-determining step. Thermodynamic and activation parameters associated with the reactions are discussed.