Complexes derived from hydrolytically ‘unstable’ hydrazone ligands – Some unexpected products

Polyfunctional ligands derived from condensation reactions in which small molecules, e.g., water, an alcohol, etc., are eliminated can suffer the ravages of hydrolytic attack on reaction with transition metal ions in aqueous based solvents, or solvents containing small amounts of water. A series of such reactions is described involving hydrazone based ligands, in which hydrolyzed ligand fragments, and their resulting coordination complexes, are produced. Structures are reported to identify these products, which reveal some unexpected ligand rearrangements. Variable temperature magnetic data are discussed for some dinuclear complexes, and a DFT study is presented to rationalize an unusual ligand transformation.