Heteroleptic Cu(II) Dipyrromethene Complexes Linked via Hydrogen Bonds, Coordinative Bonds, and Covalent Bonds: Probing the Coordination Environment by Electron Paramagnetic Resonance Spectroscopy

meso-Phenyldipyrromethene acetylacetonato copper(II) complexes [Cu(dpm-C6H4R)(acac)] (dpm-C6H4R = phenyl-substituted dipyrromethene, acac = acetylacetonato) with different substituents R at the phenyl moiety were
synthesized. These substituents determine the mode of assembly into polymeric chains, namely, via hydrogen
bonds, coordinative bonds, or covalent bonds (by immobilization on a polymer). Although the primary coordination
sphere around the copper center is essentially identical for all complexes reported in this study (square-planar
geometry with N2O2 coordination), subtle differences due to the different microenvironments have been observed
in their structures, properties, and reactivity as probed by IR spectroscopy, electron paramagnetic resonance
spectroscopy, magnetic measurements, thermal analyses, density functional theory calculations, and reaction with
pyridine.