EFFECT OF STERIC HINDRANCE IN 1 1 7 7-TETRAETHYLDIETHYLENETRIAMINE COMPLEXES OF COPPER(2)

The proton stability constants of 1,1,7,7-tetraethyldiethylenetriamine (Etidien) are slightly lower than those of dien with log K values of 9.66, 8.62, and 3.55 for Ettdien compared to 9.94, 9.13, and 4.34 for dien. On the other hand the stability con¬stant for Cu(II)-Et4dien (log K1 = 10.1) is very much less than for Cu(II)-dien (log K1 = 16.0). The ethyl groups severely hinder coordination of ligands to the out-of-plane positions of copper. The 106-fold decrease in the stability constant is attributed primarily to blocking the coordination of water in these axial positions. The log (stability constant) of [Cu-(Et4dien)OH] + is 6.0 compared to 4.9 for [Cu(dien)OH] +, which is consistent with increased binding of coordinated water in the fourth planar position due to reduced coordination of water in the axial positions. All Et4dien constants are at 25.0° and 0.1 M ionic strength. © 1968, American Chemical Society. All rights reserved.