Revisiting the Electronic Ground State of Copper Corroles

Electronic Structure of Copper Corroles

“…Figure 3a shows the cyclic voltammogram of Cu-1.T wo reversible reductions at À0. 6 ]w as produced by treating Cu-1 with AgPF 6 in CH 2 Cl 2 to give al ight yellow-brown solution. The reduced corrole exhibits as ignificant red shift of the Soret band with aconcomitant growth of the Qbands.Conversely, the intensity of the Soret band decreases and the Qb ands have virtually no intensity for the oxidized corrole (Figure 3b).…”

“…[1][2][3][4] Thee lectronic structure was later revised as afully deprotonated corrole ligand containing aCu III centre [5] due to the lack of an N-pyrrole proton by IR spectroscopy and crystallography,and the diamagnetic nature of the compound. Subsequent structural [6][7][8][9][10] and computational [11,12] studies of copper corroles with awide variety of meso and b-substituents have suggested the ground state to be best described as an antiferromagnetically coupled Cu II corrole radical cation. These studies have shown that saddling distortions are inherent to copper corroles as ac onsequence of significant overlap between the Cu d x 2 Ày 2 orbital and the corrole p HOMO.…”

“…These studies have shown that saddling distortions are inherent to copper corroles as ac onsequence of significant overlap between the Cu d x 2 Ày 2 orbital and the corrole p HOMO. [6] However,t he electronic structure of copper corroles remains an unresolved issue as ar ecent report of aone-electron-oxidized Cu corrole derivative was assigned as the first example of adiscrete Cu IV species. [13] This conclusion was derived from the assumption that the neutral corrole complex contains aC u III centre.I nt his study,w ep rovide comparative spectroscopic and magnetic data of Cu corroles, the corresponding cation and anion, and aCuisocorrole that establish the presence of Cu II across the series of complexes with the redox load borne by the macrocyclic ligand.…”

“…Themetal centre displays adistorted square planar geometry,with d(CuÀN) = 1.883-1.899 bond lengths,w hich is consistent with other Cu corrole structures. [15,16] Thec orrole adopts the typical nonplanar, saddled geometry, [6,9,10] where alternating pyrrole units point above and below the plane of the macrocycle.…”

“…[6] Brown crystals of Cu-1 suitable for X-ray diffraction were grown from at oluene solution of the compound. As ummary of the crystallographic data is provided in Table S1 in the Supporting Information (SI).…”