O. A. Reutov

Asymmetric cyclopalladation of dimethylaminomethylferrocene

Abstract Palladation of dimethylaminomethylferrocene (I) catalyzed by salts of optically active acids affords optically active planar chiral 2-dimethylaminomethylferrocenylpalladium chloride dimer (II) in high yield. Absolute rotation and optical purity of II were determined by conversion to 2-methylferrocenecarboxylic acid and 2-methylferrocenealdehyde. Factors affecting enantiomeric excess are examined and conditions for maximal asymmetric induction are found.

Structure and solvent effects in organomercuric electrochemistry. Polarographical scale of CH bond acidities

Abstract A number of organomercuric compounds, R2Hg and RHgClO4, with different R groups have been studied by the polarographic method. Both the half-wave potential, E 1 2 , and the transfer coefficient, α, are shown to be necessary for judging the CHg bond strength from the polarographic data. These data for R2Hg were used for the construction of a polarographic scale of CH bond acidities.

Reaction of the low-valent transition metal complexes with non-transition organometallic compounds☆

Abstract The zero-valent triphenylphosphine complexes of palladium and platinum were found to react readily under mild conditions with organomercurials RHgX and R2Hg. Final products appear to be σ-bonded organic derivatives of Pd and Pt. In several cazses, the relatively stable intermediates with platinum to mercury bond were isolated. Dibenzylideneacetone-palladium (0) and -platinum(0) complexes exhibits similar reactivity towards organomercurials.

The effect of solvent upon the rates and mechanisms of organometallic reactions : III. nqr specta and structures of molecular complexes of methyltin halides and tin tetrahalides

Abstract NQR spectra have been obtained for molecular complexes of methyltin halides or tin tetrahalides containing various electron-donating molecules. The structures have been shown to be a function of the number of methyl groups and halogens present in the methyltin halides and of the nature of the electron donor. An anomalous temperature dependence of the NQR frequencies has been observed in some cases.

The effect of solvent upon the rates and mechanisms of organometallic reactions. : II. Molecular complexes of methyltin halides and tin tetrahalides

Methyltin halides give solid molecular complexes with the organic solvents normally employed in organometallic chemistry. Me3SnBr gives complexes of the type Me3SnBr·L with monodentate ligands (Py, DMSO, DMF, HMPT) and complexes of the type 2Me3SnBr·L with bidentate ligands (dioxane, TMED). Me2SnHal2, MeSnHal3 and SnHal4 give complexes containing either two monodentate ligands or one bidentate ligand.

Alternative synthesis of enantiomeric 1-diphenylphosphino-2-dimethylaminomethylferrocene (Kumada's ligand)

Abstract A novel facile synthesis of enantiomeric 1-diphenylphosphino-2-dimethylaminomethylferrocene (III), an important ligand for asymmetric catalysis using metal complexes, has been developed. This substance is prepared in a two-step procedure starting with dimethylaminomethylferrocene (I), in 40% overall yield. The absolute configuration and maximum optical rotation of III are determined through the correlation with the previously described cyclopalladated amine derived from I.

Exchange of organomercury compounds with mercury metal : II. Dismutation of organomercury radicals on the surface of mercury☆

The galvanostatic method has been applied to the study of the dismutation of organomercury radicals formed by the electrochemical reduction of organomercury salts on the mercury surface. The relative stabilities of organomercury radicals have been found to follow the series AlkHg· >ArHg·, CH2CHHg· ? PhCH2Hg·. The lifetimes on the mercury surface have been determined as 10−2 to 5 x 10−2 sec for AlkHg·, 1 x 10−4 to 2 x 10−4 for ArHg· and CH2CHHg.·, and < 10(su−4) sec for PhCH(in2)- Hg·. The CHg bond in radicals on the mercury surface is more stable than that in radicals generated under homogeneous conditions. This has been attributed to the stabilising effect of the metal.

The effect of the solvent upon the rates and mechanisms of organometallic reactions : V. PMR spectra and structure of molecular complexes of methyltin halides in solutions

The complexation of methyltin halides in electron-donating solvents such as acetone, dioxane, dimethoxyethane, pyridine, dimethylformamide, dimethyl sulfoxide, hexamethylphosphoric triamide, and tetramethylethylenediamine has been studied by means of PMR spectroscopy. Equilibrium constants have been evaluated for Me3SnHal·D (D = donor) complexes. The concentration and temperature dependences of J(119SnC1H) in methyltin halides suggest some conclusions on the electron and spatial structures of complexes in solutions.Abstract The complexation of methyltin halides in electron-donating solvents such as acetone, dioxane, dimethoxyethane, pyridine, dimethylformamide, dimethyl sulfoxide, hexamethylphosphoric triamide, and tetramethylethylenediamine has been studied by means of PMR spectroscopy. Equilibrium constants have been evaluated for Me3SnHal·D (D = donor) complexes. The concentration and temperature dependences of J(119SnC1H) in methyltin halides suggest some conclusions on the electron and spatial structures of complexes in solutions.

Transition metal carbonylates in nucleophilic aromatic substitution: I. Influence of ionic association on the rates of reactions with perfluoroaromatic substrates

Abstract Quantitative yields of monosubstituted products were obtained from the reactions between CpFe(CO) 2 − (Cp = C 5 H 5 ), Re(CO) 5 − and C 6 F 6 , C 5 F 5 N; and CpW(CO) 3 − , Mn(CO) 5 − and C 5 F 5 N. The kinetics of the reactions of Re(CO) 5 − with C 6 F 6 , and of CpW(CO) 3 − and Mn(CO) 5 − with C 5 F 5 N were studied with respect to solvent, counterion, complexing agents and common ion effects. In all of the reactions studied, contact ion pairs were observed to be more reactive than solvent-separated ion pairs or free ions.

Stereochemistry of redox-demercuration of an optically active 8-(α-bromomercuriethyl)quinoline with zerovalent palladium complexes

Abstract A novel organomercurial bearing the metal atom at a chiral centre, 8-(α-bromomercuriethyl)quinoline (I) has been synthesized from the respective bromide and metallic mercury, and resolved via diastereomeric D-camphor sulphonates. Enantiomeric I has been treated with (Ph 3 P) 4 Pd 0 and (dba) 3 Pd 2 0 to give optically active chelate metallocycles II and III which had been previously known in racemic form. In both reactions, (-)I leads to (+)organopalladiums. The optical activity proves the heterolytic reaction mechanism.