Design of Ligands Which Improve Cu(I) Catalysis

Abstract

It seemed plausible that tri- and tetraamine ligands with a substituent which binds to Cu(I) but not to Cu(II), e.g., an allyl, stabilize Cu(I) in aqueous solutions and shift its redox potential cathodically relative to Cu+(aq). Therefore, the ligands N(CH2CH2NR2)2(CH2CH2NRCH2CHCH2) (R = H or CH3) were synthesized. These ligands indeed stabilize Cu(I) in aqueous solutions and shift the redox potential of the Cu(II)/Cu(I) and Cu(I)/Cu(0) couples cathodically relative to Cu2+/+(aq) and the complexes CuIIL/CuIL where L = R2NCH2CH2NRCH2CH2NR(CH2CHCH2). Therefore, the copper complexes with the new ligands are expected to be better catalysts to processes in which the redox step is the rate-determining step.