ChemInform Abstract: THE EFFECT OF N‐ALKYLATION ON THE PROPERTIES OF FIVE‐COORDINATE COPPER(II) COMPLEXES OF TETRAAMINE LIGANDS

Abstract

Anhand von EPR‐ und elektronenspektroskopischen Untersuchungen der fünffach‐koordinierten quadratisch‐pyramidalen (Ia) und trigonalbipyramidalen Komplexe (Ib) in Lösung und in festem Zustand wird der Einfluß der N‐Substituenten auf die Geometrie der CuN4X‐Chromophore und die spektroskopisch Reihe diskutiert.

A Kinetico-Mechanistic Study on CuII Deactivators Employed in Atom Transfer Radical Polymerization

“…61 While no crystal structures are currently available for complexes bearing the Et 6 tren ligand, EPR measurements reveal that trigonal bipyramidal geometry is conserved in solution. 30,31 Interestingly, while [Cu II (tren)X] n+ complexes react via an I a mechanism, 63,64 increasing the steric bulk by methylation of the three terminal amines (Me 6 tren) produces a definite shift toward an I d mechanism, as shown for DMF and diethylformamide interchange 65,66 or azide− and thiocyanate−water substitution. 67 The intermediate bulk of the Me 3 tren complexes (with three terminal secondary amines, Figure 8) appears to still generate substitutions via an associatively activated I a mechanism, 68 thus illustrating a subtle mechanistic tuning as a function of steric hindrance in the vicinity of the exchanging coordination site.…”