Bis-copper(II) Complex of Triply-linked Corrole Dimer and Its Dication.

Copper complexes of corroles have recently been a subject of keen interest due to their ligand non-innocent character and unique redox properties. Here we investigated bis-copper complex of a triply-linked corrole dimer that serves as a pair of divalent metal ligands but can be reduced to a pair of trivalent metal ligands. Reaction of triply-linked corrole dimer 2 with Cu(acac)2 (acac=acetylacetonate) gave bis-copper(II) complex 2Cu as a highly planar molecule with a mean-plane deviation value of 0.020 Å, where the two copper ions were revealed to be divalent by ESR, SQUID, and XPS methods. Oxidation of 2Cu with two equivalents of AgBF4 gave complex 3Cu, which was characterized as a bis-copper(II) complex of a dicationic triply-linked corrole dimer not as the corresponding bis-copper(III) complex. In accord with this assignment, the structural parameters around the copper ions were revealed to be quite similar for 2Cu and 3Cu. Importantly, the magnetic spin-spin interaction differs depending on the redox-state of the ligand, being weak ferromagnetic in 2Cu and antiferromagnetic in 3Cu.