Structural characterization, ROS-inductive and proteasome inhibitory properties of ternary and binary copper(II) complexes of N2- and N2O2-ligands

Macrocycle-Induced Modulation of Internuclear Interactions in Homobimetallic Complexes

“…Across the series, the coordination environment around each metal center is pseudo -octahedral, with two cis μ-Cl ligands occupying axial and equatorial coordination sites (defined with respect to the PDI unit as occupying three equatorial sites) and a solvent molecule occupying the second axial site on each metal atom (Figure , solvent identity noted in Table ). This coordination geometry stands in contrast to most mononuclear, divalent 3d-metal PDI complexes, and similar mer -N 3 chelating ligands, such as terpyridines, pyridyl-bis­(oxazoline), and pyridyl-bis­(pyrazole) variants, in which the outer set of coordinating nitrogens either serves as the axial ligands in a trigonal bipyramidal structure or as part of a square pyramidal coordination environment. − The limited examples of octahedral geometries are usually the result of significant intermolecular π–π stacking, − intermolecular hydrogen bonding, ,− or when in the presence of pendant coordinating arms (such as pyridine or acetate groups). ,− In the absence of these effects, only the aforementioned five-coordinate geometries are reported, indicating that the steric constraint imposed by the macrocyclic ligand architecture is an important factor in creating the observed pseudo -octahedral geometries.…”