Thermodynamical Characteristics and Molecular Structures of 3d-element Macrocyclic Complexes Containing Phthalocyanine, Oxo, and Fluoro Ligands: DFT Consideration

Establishing the fundamental possibility of the existence of the heteroligand macrotetracyclic complexes of vanadium, chromium, manganese, and iron-containing in the inner coordination sphere phthalocyanine, oxygen (O<sup>2-</sup>) and fluorine (F-) ions and having general [MPc(O)F] formula (M= V, Cr, Mn, Fe), by using of quantum-chemical calculation of parameters of their molecular/electronic structures and thermodynamical characteristics. The molecular and electronic structures of the above-mentioned heteroligand macrotetracyclic chelates of 3d-elements (M) of the type [MPc(O)F] (M= V, Cr, Mn, Fe) which are unknown at present, were theoretically investigated. Standard thermodynamic parameters of formation (standard enthalpy ΔH<sup>0</sup><sub>f, 298</sub>, entropy S<sup>0</sup><sub>f, 298</sub>, and Gibbs’s energy ΔG<sup>0</sup><sub>f, 298</sub>) for these macrocyclic compounds were calculated, too. Identifying details of molecular and electronic structures of compounds indicated above. Density functional theory (DFT) model chemistries (B3PW91/TZVP and OPBE/TZVP) with a combination of the D3 version of Grimme’s dispersion. The data on the geometric parameters of the molecular structure of these complexes are presented; it was shown that MN4 chelate nodes, all metal-chelate and 6-membered non-chelate rings in each of these macrocyclic coordination compounds, are practically planar with a small deviation from coplanarity (not more 3°); nonetheless, N4 grouping from donor nitrogen atoms and 5-membered non-chelate rings are strictly planar. Wherein, the bond angles between two donor nitrogen atoms and M atom are not equal to 90o; a similar situation occurs for the bond angles between donor atoms N, M, and O or F (notwithstanding the bond angles formed by M, O, and F atoms are exactly 180°). Also, NBO analysis data and the values of the standard enthalpy, entropy, and Gibbs energy of the formation of these compounds were presented. Specific features of DFT calculated molecular and electronic structures of the heteroligand metal macrocyclic compounds have been discussed. It has been shown that good agreement between the parameters of molecular structures obtained by two various DFT model chemistries takes place. Also, it has been noted that predicting the possibility of the existence of exotic coordination compounds and modeling their molecular/electronic structures using modern quantum chemical calculations (and, in particular, using DFT of various levels) is a very useful tool for solving problems associated with such synthesis.