Nickel(II) and copper(II) complexes based on N-(2-carboxyethyl)alkanolamines: Influence of the amino alcohol structure on the coordination sphere of the metal center

New nickel(II) complexes based on N-(3-hydroxypropyl)-β-alanine, N-(bis(hydroxymethyl)methyl)-β-alanine, and N-(tris(hydroxymethyl)methyl)-β-alanine are synthesized, and their structures are studied by X-ray diffraction analysis. The coordination spheres of the nickel and copper metal centers in the condensed phase are compared for a series of N-substituted β-alaninate ligands with the regularly changed dentate mode. In the case of the copper(II) complexes, an increase in the size of the alkanolamine chelate ring or the number of hydroxymethyl groups provides the formation of achiral coordination structures, whereas the structures of the nickel(II) complexes are independent of the size of the alkanolamine chelate ring or the number of hydroxymethyl groups, thus providing the formation of the complexes as racemic modifications.