On the Structure, Electrochemistry, and Spectroscopy of the (<i>N</i>,<i>N‘</i>-Bis(2‘-(dimethylamino)ethyl)-<i>N</i>,<i>N‘</i>-dimethylpropane-1,3- diamine)copper(II) Ion

The synthesis, spectroscopy, and electrochemistry of the acyclic tertiary tetraamine copper(II) complex [CuL1](ClO4)2 (L1 = N,N‘-bis(2‘-(dimethylamino)ethyl)-N,N‘-dimethylpropane-1,3-diamine) is reported. The X-ray crystal structure of [CuL1(OClO3)2] reveals a tetragonally elongated CuN4O2 coordination sphere, exhibiting relatively long Cu−N bond lengths for a CuII tetraamine, and a small tetrahedral distortion of the CuN4 plane. The [CuL1]2+ ion displays a single, reversible, one-electron reduction at −0.06 V vs Ag/AgCl. The results presented herein illustrate the inherent difficulties associated with the separation and characterization of CuII complexes of tertiary tetraamines, and some previously incorrect assertions and unexplained observations of other workers are discussed.