Potentiometric and spectrophotometric titration of Cu 2+ complexes with N ‐isopropyl‐2‐methyl‐1,2‐propanediamine

The complexation of Cu 2+ by N ‐isopropyl‐2‐methyl‐1,2‐propanediamine (L) has been studied by potentiometric and spectrophotometric titration. The dominant complexes formed in this system are [CuL] 2+ , [CuL 2 ] 2+ , [Cu 2 L 2 (OH) 2 ] 2+ , and [CuL(OH) 2 ]. The data were thoroughly tested for different models with [CuL(OH)] + , [CuL(OH)] + , [Cu(OH)] + , and [Cu 2 (OH) 2 ] 2+ as additional species. The importance of steric factors is indicated by the d‐d* spectra: for [CuL 2 ] 2+ , (λ max = 499 nm) the absorption maximum is shifted by 50 nm to high energies relative to [Cu(en) 2 ] 2+ , (λ max = 549 nm), whereas the opposite is true for the 1:1 complexes ([CuL] 2+ : λ max = 712 nm,s [Cu(en)] 2+ : λ max = 660 nm).