Heteroligand Iron(V) Complexes Containing Porphyrazine, trans-Di[benzo]porphyrazine or Tetra[benzo]porphyrazine, Oxo and Fluoro Ligands: DFT Quantum-Chemical Study

Abstract

By using quantum chemical calculation data obtained by the DFT method with the B3PW91/TZVP and OPBE/TZVP levels, the possibility of the existence of three Fe(V) complexes, each of which contains in the inner coordination sphere porphyrazine/trans-di[benzo]porphyrazine/tetra[benzo]porphyrazine (phthalocyanine), oxygen (O2−) and fluorine (F−) ions, was shown. Key geometric parameters of the molecular structure of these heteroligand complexes are given; it is noted that FeN4 chelate nodes, and all metal-chelate and non-chelate cycles in each of these compounds, are practically planar with the deviation from coplanarity, as a rule, by no more than 0.5°. Furthermore, the bond angles between two nitrogen atoms and an Fe atom are equal to 90°, or less than this by no more than 0.1°, while the bond angles between donor atoms N, Fe, and O or F, in most cases, albeit insignificantly, differ from this value. Nevertheless, the bond angles formed by Fe, O and F atoms are exactly 180°. It is shown that good agreement occurs between the structural data obtained using the above two versions of the DFT method. NBO analysis data for these complexes are presented; it is noted that, according to both DFT methods used, the ground state of the each of three complexes under consideration may be a spin quartet or spin doublet. Additionally, standard thermodynamic parameters of formation (standard enthalpy ∆fH0, entropy S0 and Gibbs’s energy ∆fG0) for the macrocyclic compounds under consideration are calculated.

Coordination compounds with subporphyrazine may exist: DFT quantum chemical prediction for M(ii) complexes with a given macrocyclic ligand (M = Ti–Zn)

“…The calculations were carried out using the Gaussian09 program package. 48 As in our previous articles, in which the DFT method of calculation was used, 34–37 the correspondence of the found stationary points to the energy minima in all cases was proved by calculating the second derivatives of the energy to the coordinates of the atoms; herein, all equilibrium structures corresponding to the minimum points on the potential energy surfaces had only real (and, moreover, always positive) frequency values. Among the optimized structures for further consideration, the one with the lowest total energy was selected.…”

“…The version of the DFT method, namely, DFT with the B3PW91 functional described in detail in, [30][31][32] which combines the standard extended split valence basis set TZVP 33 and has already been used before by us, in particular, in, [34][35][36][37] was also used in this work. The use of the given version of the DFT method in this case is because according to, [30][31][32] it allows one to obtain the most accurate (i.e., close to experimental) values of the geometric parameters of molecular structures as well as much more accurate values of thermodynamic and other physicochemical parameters in comparison with other variants of the DFT method.…”

“…The version of the DFT method, namely, DFT with the B3PW91 functional described in detail in, 30–32 which combines the standard extended split valence basis set TZVP 33 and has already been used before by us, in particular, in, 34–37 was also used in this work. The use of the given version of the DFT method in this case is because according to, 30–32 it allows one to obtain the most accurate ( i.e.…”