Synthesis, X-ray crystal structure, and properties of antipyrinium perchlorates, hexakis(antipyrine)thulium- and hexakis(antipyrine)ytterbium perchlorates. Quantum-chemical studies of ligands protonation

Protonation of the bioactive ligand-antipyrine (AP, 2,3-dimethyl-1-phenyl-3-pyrazolin-5-one) has been considered, the crystal packing specific features for the protonated antipyrine perchlorate compounds ([APH]ClO4 · H2O (1, 2) and [AP2H]ClO4 (3, 4)), as well as the crystal structure particularities for [Tm(AP)6](ClO4)3 (5) and [Yb(AP)6](ClO4)3 (6) have been elucidated. The protonation ability—complex formation ability relationship has been revealed for a number of organic ligands. Quantum-chemical calculations (DFT) and comparison with the experimental data allowed aligning some organic ligands in a row according to their ability to be protonated and to be incorporated into the inner coordination sphere of the complex.