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

Determination of the Absolute Configuration of CN-Palladacycles by 31P{1H} NMR Spectroscopy Using (1R,2S,5R)-Menthyloxydiphenylphosphine as the Chiral Derivatizing Agent: Efficient Chirality Transfer in Phosphinite Adducts

A series of (1R)-MenOPPh2 phosphinite derivatives of α-arylalkylaminate CN-palladacycles of known absolute configuration was prepared. Their structure and stereochemistry were determined using different experimental (NMR spectroscopy and X-ray diffraction) and theoretical (density functional theory calculation) methods. Despite the conformational mobility of the phosphinite reagent and the highly remote position of its stereocenters from those of the cyclopalladated amine, efficient chirality transfer in the phosphinite cyclopalladated complexes was established. On the basis of these results, a new method for the determination of the absolute configuration of chiral CN-palladacycles was elaborated using the (1R)-MenOPPh2 phosphinite as a highly sensitive referee ligand and in situ 31P{1H} NMR spectroscopy as a control method. The proposed approach is a remarkable addition to the classical NMR techniques, increasing their versatility and excluding the isolation of the phosphinite derivatives. © 2016 American Chemical Society

The use of control experiments as the sole route to correct the mechanistic interpretation of mercury poisoning test results: The case of P,C-palladacycle-catalysed reactions

In the study of the metallic mercury interaction with cyclopalladated derivatives of tris-ortho-tolylphosphine [{(κ2P,C-L)Pd(μ-X)}2], the redox-transmetallation of palladacycles by metallic mercury with the formation of P,C-chelated benzylmercurials [(κ2P,C-L)HgX] was revealed at moderate temperature in the presence of excess Hg(0). In contrast, the mercury(0) testing of the Suzuki reaction with the same chloride P,C-precatalyst gave a negative result, even at a higher temperature and with a greater excess of Hg(0). The structures of these mercurials have been convincingly confirmed spectrally (1Н, 13С, 31Р and 199Hg NMR), and via X-ray diffraction study and DFT calculations for the chloride mercurial. Our results and the analysis of known data on the mercury diagnostics of catalytic systems with classical and anomalous P,C-precatalysts enable us to assume that the intact state of palladacycle is present in the key anionic intermediate [(κ2P,C-L)Pd0]– of catalytic cycles of the Suzuki and Heck reactions and a lower reactivity of Hg(0) with palladium(0) complexes in comparison with that of palladium(II) analogues. © 202

Determination of the Absolute Configuration of CN-Palladacycles by 31P{1H} NMR Spectroscopy Using (1R,2S,5R)-Menthyloxydiphenylphosphine as the Chiral Derivatizing Agent: Efficient Chirality Transfer in Phosphinite Adducts

A series of (1R)-MenOPPh2 phosphinite derivatives of α-arylalkylaminate CN-palladacycles of known absolute configuration was prepared. Their structure and stereochemistry were determined using different experimental (NMR spectroscopy and X-ray diffraction) and theoretical (density functional theory calculation) methods. Despite the conformational mobility of the phosphinite reagent and the highly remote position of its stereocenters from those of the cyclopalladated amine, efficient chirality transfer in the phosphinite cyclopalladated complexes was established. On the basis of these results, a new method for the determination of the absolute configuration of chiral CN-palladacycles was elaborated using the (1R)-MenOPPh2 phosphinite as a highly sensitive referee ligand and in situ 31P{1H} NMR spectroscopy as a control method. The proposed approach is a remarkable addition to the classical NMR techniques, increasing their versatility and excluding the isolation of the phosphinite derivatives. © 2016 American Chemical Society

N '-Sulfonyl- and N '-Acylhydrazones of alpha- and beta-Diphenylphosphorylalkanones: Synthesis and Structure

The interaction of saturated acyclic alpha- and beta-(diphenylphosphoryl)alkanones with sulfonyl- and acylhydrazines has led to the corresponding hydrazones in yield up to 90%. Structure of the obtained compounds has been elucidated using the data of single-crystal X-ray diffraction analysis and NMR spectroscopy

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