Chiral Tetraamines Based on (S)-2-(Aminomethyl)pyrrolidine: Template synthesis and properties of copper(II) complexes

The template reaction of {bis[(S)-2-(aminomethyl)pyrrolidine]}copper(II) with formaldehyde, nitroethane, and base in MeOH yields optically pure {1,7-bis[(S)-pyrrolidin-2-yl]-4-methyl-4-nitro-2,6-diazaheptane}-copper(II) ([Cu((S,S)-mnppm)]2+) in high yield. The same reaction with rac-2-(aminomethyl)pyrrolidine is also described. Preparative details and spectroscopic and electrochemical properties of the Cu(II) complexes and of the free ligands are reported and compared with structural, spectroscopic, and electrochemical data of the Cu(II) complex of the unsubstituted parent ligand 1,7-bis[(S)-pyrrolidin-2-yl]-2,6-diazaheptane (ppm). The crystal structure of [CU(PPM)]Cl.ClO4 has been determined by X-ray diffraction methods.