Novel Macrocyclic Metal Complexes Containing Octafluoro-Substituted Porphyrazine and Two Axial Acido Ligands: Design Using DFT

Abstract

Using three independent variants of the density functional theory (DFT) with the B3PW91, M06, and OPBE functionals and the TZVP basis set, the molecular structures of heteroligand (6666) macrotetracyclic chelates of 3d metals of the [M(OFP)(F)₂] type (M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu) with a doubly deprotonated form of the tetradentate macrocyclic ligand, octafluoroporphyrazine (OFP^2–), and two axially oriented fluoro ligands were calculated. Selected bond lengths and bond and nonbonded angles in the resulting metal complexes are presented. According to data from all the above-mentioned DFT methods, seven of these eight complexes have a planar MN4 chelate core and a planar macrocycle structure. Moreover, all five-membered and six-membered rings in each of these seven metal chelates are identical to each other (both in the sum of their bond angles and in their range). An NBO analysis of the coordination compounds under consideration, was performed, images of their highest occupied (HOMO) and lowest unoccupied (LUMO) molecular orbitals, as well as the values of the effective charges on individual atoms, are presented. The standard enthalpy, entropy, and Gibbs free energy of formation of these compounds were calculated. It was found that the values of the standard enthalpy and standard Gibbs energy for both the H₂OFP ligand itself and the metal complexes it forms are negative, which indicates their high thermodynamic stability. There is good agreement, both qualitative and quantitative, between analogous parameters calculated by various DFT methods.