3d-Unusual Macrotetracyclic Chelates of 3d Elements with a 17-Membered Macrocyclic Ligand and Their Molecular Structures in Terms of DFT Quantum-Chemical Simulation

The molecular structures of macrotetracyclic M(II) (M = Mn, Fe, Co, Ni, Cu, or Zn) chelates with a 17-membered tetradentate macrocyclic ligand with the (NNNN) coordination of donor centers, containing one 5-membered, one 8-membered, and two 6-membered chelate rings were calculated by the DFT OPBE/TZVP method. Most important bond lengths, bond angles, and nonbonding angles in the complexes are reported. The standard enthalpy, entropy, and Gibbs free energies were calculated for these complexes. Prominent non-coplanarity is intrinsic to all complexes, both in chelate cores MN4 and in chelate rings. In each of the complexes the 5-membered chelate ring has a relatively small non-coplanarity, the 8-membered chelate ring has considerable non-coplanarity, and 6-membered rings are intermediate in this regard, being quite strongly differentiated in their degrees of non-coplanarity.