New Metal Chelates with Sterically Hindered Azo Ligands:Synthesis and Physicochemical Properties

摘要

Metal chelates based on 3,5-di-(tert-butyl)-2-hydroxyazobenzene are synthesized and their physicochemical properties were studied.Four alternative structures and isomeric transformations between these structures were suggested on the basis of NMR data,electric dipole and magnetic moments,X-ray diffraction and quantum-chemical data.The change in stereochemistry of a complex through introduction of tert-butyl sub-stituents was found to give unusual (for metal chelates with azo ligands (MN_2O_2)) dome-shaped isomers with the trans-planar coordination core at a vertex or with a distorted cis-structure.