Design of ligands that stabilize Cu(I) and shift the reduction potential of the Cu^II/I couple cathodically in aqueous solutions

The ligands R₂NCH₂CH₂N(R)CH ₂CH₂N(R)CH₂CHdCH₂, where R = H, CH₃, were synthesized. The stability constants of their complexes with Cu(II) and Cu(I) in aqueous solutions were determined. Both ligands stabilize Cu(I) in aqueous solutions, though the reduction potentials of both (CuLi)^2+/+ couples are shifted cathodically in comparison to the Cu^2+/+_aq couple. These properties indicate that these complexes should be good catalysts for a variety of processes that are catalyzed by Cu(I).