Some metal-ion complexes with ligands formed by reaction of amines with aliphatic carbonyl compounds. Part IV. Some compounds of nickel(II) and copper(II) formed by the diaminoethane–butanone reaction

Abstract

Bis(diaminoethane)nickel(II) perchlorate reacts with butanone (ethyl methyl ketone) at room temperature to yield the bis complex of the β-aminoketone NH₂·CH₂·CH₂·NH·C(CH₃)(CH₂·CH₃)·CH₂·CH₂·CH₃ which acts as a tridentate ligand. In pyridine this undergoes intramolecular imine formation to yield the nickel(II) complex of 5,7,12,14-tetraethyl-7,14-dimethyl-1,4,8,11-tetra-azacyclotetradeca-4,11-diene (2). The first reaction at higher temperatures, or in the presence of co-ordinating anions (e.g. Cl^–, NO₃^–, NCS^–) or solvents (e.g. methanol, methyl cyanide, pyridine) yields the complex of the tetradentate ligand NH₂·CH₂·CH₂·N:C(CH₂·CH₃)·CH₂·C(CH₃)(CH₂·CH₃)·NH·CH₂·CH₂·N:C(CH₃)·CH₂·CH₃, from which the imino group can be hydrolysed to yield the complex of the ligand NH₂·CH₂·CH₂·N:C(CH₂·CH₃)CH₂·C(CH₃)(CH₂·CH₃)·NH·CH₂·CH₂·NH₂, (1). The salt [H₂(2)](ClO₄)₂, crystallizes when [H(en)]ClO₄ is reacted with butanone, and the compounds [Ni(2)](ClO₄)₂ and [Cu(2)](ClO₄)₂ were prepared by reaction of this with the metal acetates. Tris(diaminoethane)nickel(II) perchlorate reacts extremely slowly with butanone to yield the complex of 5,7,12,14-tetraethyl-7,12-dimethyl-1,4,8,11-tetra-azacyclotetradeca-4,14-diene (3), a geometrical isomer of (2). The large difference in the apparent rate of the last reaction compared with the equivalent reaction with acetone is discussed.