- Investigations on syntheses and reactions of fluorophenylmercury compounds with the ligands 2-FC6H4, 2,6-F2C6H3, and 2,4,6-F3C6H2
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2,6-F2C6H3HgCl and 2,4,6-F3C6H2HgCl are synthesized via the reactions of the corresponding phenylmagnesium compounds and HgCl2. 2-FC6H4HgCl is selectively obtained only in a reaction involving intermediately formed Cd(2-FC6H4)2. The diphenylmercury derivative Hg(2,4,6-F3C6H2)2 is obtained while stirring a dichloromethane solution of 2,4,6-F3C6H2HgCl for several days. The direct mercuration of 1,3,5-trifluorobenzene with Hg(OCOCF3)2 yields, depending on the stoichiometry, 2,4,6-trifluorophenylmercury trifluoroacetate and 1,3-bis(trifluoroacetatomercuri)-2,4,6-trifluorobenzene which is converted into the corresponding chloromercuri derivative by treatment with hydrochloric acid in CH3CN. As a product of the reaction of 1,3,5-trifluorobenzene and HgO in CH3OOH only 2,4,6-trifluorophenylmrcury acetate is isolated although spectroscopic evidence has been found for double and triple mercurated derivatives. All compounds are characterized by elemental analyses, nmr and mass spectra. Th reaction of Hg(2,4,-F3C6H2)Cl and Cd(CF3)2 · 2 CH3CN gives Hg(2,4,6-F3C6H2)CF3 which slowly dismutates in CH2Cl2 solution into Hg(2,4,6-F3C6H2)2 and Hg(CF3)2. The ligand exchange of Hg(2,4,6-F3C6H2)2 and TeCl4 selectively gives Te(2,4,6-F3C6H2)2Cl2 and Hg(2,4,6-F3C6H2)Cl. Transmetalations of Hg(2,4,6-F3C6H2)2 and gallium or tin give NMR spectroscopic evidence for the new derivates Ga(2,4,6-F3C6H2)3 and Sn(2,4,6-F3C6H2)4.
- Layeghi, Hamid,Tyrra, Wieland,Naumann, Dieter
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p. 1601 - 1610
(2008/10/09)
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- Organotin compounds X. Organotin hydride addition to methyl cyclohexene-1-carboxylate and methyl indene-3-carboxylate
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Free radical hydrostannation of methyl cyclohexene-1-carboxylate (I) and methyl indene-3-carboxylate (III) with trialkyltin hydrides, R3SnH (R=Me, n-Bu, Ph) gives the energetically unfavourable cis products, 2-trialkylstannyl cyclohexanecarboxylate (II) 2-trialkylstannyl indene-1-carboxylate (IV) in high yields, via a trans addition of the thin hydrides.The hydride abstractions by the intermediate trialkylstannylcyclohexanyl (VIII) and trialkylstannylindanyl (IX) intermediate radicals take place stereospecifically, and exclusively from the less hindered ring side.The structures of the isomers II and IV were established by (a) their transformation into the corresponding chlorodialkylstannylderivatives V and VI, which were shown spectroscopically to have cis stereochemistries by intramolecular complexation of the ester group, and (b) their NMR data.Full 1H, 13C, and 119Sn NMR data are given.
- Ayala, A. D.,Giagante, N.,Podesta, J. C.,Neumann, W. P.
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p. 317 - 330
(2007/10/02)
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- Electron-Transfer Activation in Electrophilic Mechanisms. Cleavage of Alkylmetals by Mercury(II) Complexes
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The disappearance of the transient charge-transfer (CT) absorption bands coincides with the electrophilic (SE2) cleavage of homologous series of alkyltin compounds by various mercury(II) halides, cyanide, and carboxylates.The second-order kinetics for HgCl2 cleavage afford rate constants which vary in a rather unaccountable way with the structure of the alkyltin compound and with the polarity of the solvent.Furthermore, the relative reactivities of these alkyltin compounds in the analogous electrophilic cleavage by I2 or Br2 show poor correlations with HgCl2 cleavages, in different solvents.However, the description of the activation process as an electron transfer in the precursor complex, e.g., -> +HgCl2->, stems from the CT transition energy and leads to a linear free energy relationship in which the activation free energy is equal to the driving force for the formation of the ion pair.The latter is readily dissected by eq 18 into separate changes in electronic, steric and solvation energies.With this mechanistic formulation, the reactivities of various alkyltin compounds follow a remarkably simple linear correlation with the ionization potentials and the solvent effects, in the comparison with I2 and Br2 cleavages.Moreover, the reactivities of the various mercury(II) derivatives relate directly to differences in their electron affinities.
- Fukuzumi, S.,Kochi, J. K.
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p. 7290 - 7297
(2007/10/02)
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