Stereochemistry in Functionalized Macrocycle Complexes: Control of Hydroxyl Substituent Orientation

Use of a hydroxyl-functionalized open chain tetramine in a template reaction based on its Cu(II) complex leads,
after reduction, to a new tetraaza macrocycle with both amino and hydroxyl substituents. The macrocycle is formed
predominantly as its trans (anti) isomer, though the cis form is detectable and both have been structurally characterized
in the form of their metal complexes. Although both the Cu(II) and the Co(III) complexes of the tetramine precursor
ligand have the hydroxyl group in an axial position of a chair six-membered chelate ring, the trans macrocycle
forms Co(III) complexes with this substituent in both equatorial and axial positions.