Coordination Compounds of 3d Elements with Subphthalocyanine: A Quantum-Chemical Consideration Using DFT

Based on quantum chemical calculations using DFT model chemistries at the M06/TZVP, B3PW91/TZVP, and OPBE/TZVP levels, we have demonstrated the potential existence of (666)macrotricyclic complexes, each containing a doubly deprotonated form of subphthalocyanine (H2SPc) in the inner coordination sphere with a metal-to-ligand ratio M(II) : SPc2– = 1 : 1. The main geometric parameters of the molecular structures of these coordination compounds are presented, revealing that the chelate MN3 unit adopts a trigonal-pyramidal geometry with a substantial deviation from coplanarity (in most cases, exceeding 90°). The 6-membered metal chelate and 5-membered non-chelate rings in these complexes are also non-planar, although their deviations from coplanarity are considerably smaller, not surpassing 20° and 5°, respectively. Furthermore, the complexes can be divided into two groups. In the first group (M = Ti, V, Mn, Co, Ni, Cu, Zn) all M–N bond lengths, bond angles (NMN) in the chelate unit MN3, and non-valence angles between the coordinated nitrogen atoms are virtually up identical. In contrast, the second group (M = Cr, Fe) exhibits noticeable differences in these parameters. Good agreement between the structural data obtained using the three above-mentioned DFT method variants is established, both qualitatively and quantitatively. NBO analysis data for these complexes are presented; it is noted that according to each of the DFT methods used, the ground state of each of the complexes under consideration has the same spin multiplicity as the ground state of the corresponding central ion M(II). The standard thermodynamic parameters of formation (standard enthalpy ΔfH0, entropy S_f⁰ , and Gibbs energy ΔfG0) for these metal macrocyclic compounds were also calculated.