Apical Ligand Effects on the Electronic Structure of Cobalt(III) Corroles

NEUMAN, NICOLÁS I; CEROLINI, JUAN F. ; SANTIAGO E. VAILLARD; SARKAR, BIPRAJIT

Mülheim an der Ruhr

Workshop; 7th Orca Users Meeting; 2021

Max Planck Institut für Kohlenforschung

Corroles are porphyrinoid macrocycles with rich redox and spectroscopic properties, capable of forming complexes with a variety of elements. Transition metal corrolates tend to stabilize the metal ion in a formal M(III) oxidation state. In these complexes the ligands can act innocent, in which case the corrole has three negative charges and the metal has a real oxidation state of III; or not-innocent, in which case the ligand presents a radical dianionic character and the metal a +II oxidation state, in an open-shell configuration.Cobalt(III) corroles are one of the most commonly studied types of metallocorroles, and complexes have been obtained with a variety of apical ligands, including PPh3, Py2, DMSO, CN?, NH3, among others, several of which with reported crystal structures. In most of these cases the corroles act as innocent ligands, but in other cases the appropriate description is not so clear.In this work we will utilize wave-function based electronic structure calculations (CASSCF/NEVPT2), to analyse the effect of different apical ligands on the energy and spin states of a series of cobalt(III) corroles, some of whose crystal structures have been reported previously by us. We will briefly discuss the ligand fields acting on the central Co(III) ion when different apical ligands and corrole substituents are present. Figure 1 shows structures of the complexes of the 5,15-bis(4-nitrofenil)-10-(2-metilcarboxifenil)corrol (H31) ligand with Co(III) and one apical dimethylsulfoxide (1DMSO) [1] or two pyridine (1Py2) [2] molecules, together with a diagram of the active space orbitals employed in a CASSCF/NEVPT2 calculation of the electronic structure of 1DMSO.