When Applying the Mercury Poisoning Test to Palladacycle-Catalyzed Reactions, One Should Not Consider the Common Misconception of Mercury(0) Selectivity

The aim of this study was to demonstrate the absolute necessity of control experiments for a correct interpretation of mercury drop test results when applied to mechanistic studies of palladacycle-catalyzed reactions. It was shown that the interaction of diverse azapalladacycles with metallic mercury leads to the formation of organomercuric chlorides during the redox-transmetalation process. The structure of these organomercurials was confirmed by elemental analysis, 1H, 13C{1H}, and 199Hg{1H} NMR spectra, X-ray diffraction analysis, and DFT calculations. The behavior and properties of C,N-mercuracycles bearing the weak and labile N···Hg bond are discussed on the basis of the temperature dependence of the NMR spectra and calculated thermodynamic parameters of the dechelation process. © 2018 American Chemical Society.