Tautomerism of metal complexes with quinalizarin

The formation of complexes with quinalizarin was found to occur through the peri-hydroxycarbonyl groups with participation of tautomers and conformers. The diversity of the electronic absorption spectra of quinalizarin complexes is explained not only by the ligand ionization degree but also by the shifts in the tautomeric and conformer equilibria. The classification of the known quinalizarin complexes is suggested on the basis of spectrophotometric data and quantum-chemical calculations of the π l ,π*-band position by the Pariser-Parr-Pople method. © 2007 Pleiades Publishing, Ltd.