Reactions of the metal complexes of 2-hydroxymethylenecyclohexanone and its derivatives with amines

Abstract

I.r. and reflectance spectra of the anhydrous cobalt(II) and zinc(II) complexes of 2-hydroxymethylenecyclohexanone suggest oligomeric structures whilst the dihydrates of the cobalt(II) and nickel(II) complexes are octahedral monomers. The β-keto-amines 2-phenyl-, 2-(4-methoxyphenyl)-, 2-(4-methylphenyl)-, and 2-(1-naphthyl)-aminomethylenecyclohexanone form complexes of the general formula M(LH)₂X₂ with cobalt(II) and zinc(II) halides in which they behave as unidentate ligands, co-ordination occurring via the vinylogous amide carbonyl group. Heating bis-(2-hydroxymethyleneclohexa-1,3-dionato)nickel(II) with ethylenediamine gives the nickel complex of the macrocycle 1,12-dioxodicyclohexa[em][1,4,8,11]tetra-azacyclotetradeca[4,6,12,14]tetraene. Bis(salicylaldehydato)cobalt(II) and nickel(II) form 1 : 1 adducts with 2,3-diaminoanthraquinone in ethanol which are converted into the Schiff-base complexes on heating in Cellosolve. Mechanistic implications are discussed.