Synthesis and EPR characterisation of a 5,6-Dioxo-5, 6-<i>Seco</i>-Heptamethyl CuII byrinate

This short communication describes the synthesis of a novel 5,6-dioxo-5,6-seco-heptamethyl cu[Formula: see text]byrinate (Cu-1[Formula: see text] using a previously described ring-opening-demetallation-remetallation strategy of the corrin macrocycle. The paramagnetic seco-cu[Formula: see text]rrin is characterized by UV-vis, high-resolution mass spectrometry, and electron paramagnetic resonance (EPR) spectroscopy. The coordination geometry of Cu(II) is square-planar, with a metal-centered spin density that is partially delocalized on the corrin ligand.