The thiolate anion as a nucleophile Part VIII. Reactions of dibromotetrafluorobenzenes

The reactions of the isomeric dibrometetrafluorobenzenes with the methanethiolate anion and copper(I) methanethiolate have been examined. Using the thiolate anion replacement of fluorine by the SMe group occurred, but with copper(I) methanethiolate protodebromination and replacement of the bromine with the SMe group occurred. The new compounds isolated have been characterized and their spectra (NMR, IR, and mass) examined.     

The thiolate anion as a nucleophile Part IX. Reactions of some fluoroaromatics

The reactions of some halogenoaromatic compounds, mainly fluoroaromatics C₆F_xH_6-x with the methanethiolate anion have been studied in DMF or an HMPA/THF mixture. Complete replacement of fluorine occurred forming C₆(SMe)_xH_6-x. Attempts to prepare C₆(SEt)₆ and compounds such as C₆(SEt)₂(SMe)₄ are described. Other new compounds isolated included C₆(SMe)₅SH and C₆F₂(SMe)₂(SEt)₂. Details of the spectra, particularly NMR, are given.     

The thiolate anion as a nucleophile Part III. Reactions with various fluorobenzenes

The reactions of the fluorobenzenes, C₆F₅H, o-C₆H₂F₄, m-C₆H₂F₄, p-C₆H₂F₄, 1,3,5-C₆F₃H₃, 1,2,4-C₆F₃H₃, o-C₆F₂H₄, m-C₆F₂H₄, p-C₆F₂H₄ and C₆F₅H with thiolate anion nucleophiles RS^? (primarily MeS^?), have been studied in ethylene glycol/pyridine mixtures as a solvent. Multiple replacement of fluorine atoms was observed in the more highly fluorinated compounds, but in all cases two aromatic fluorine atoms were not replaced. Difluorobenzene and fluorobenzene did not react. The product orientations have been deduced from their NMR spectra. The mass spectra of the isomeric products C₆F₂H₃(SMe), C₆F₃H₂(SMe) and C₆F₂H₂(SMe)₂ have been examined.     

The thiolate anion as a nucleophile Part IV. Reactions of some pentafluorophenyl compounds

Direct nucleophilic substitution with sodium methanethiolate of the pentafluorophenyl compounds C₆F₅X (X = Cl, Br, I. NO₂, NH₂, CO₂H, SC₆F₅, OMe, OH) has given varying amounts of XC₆F₄(SMe), XC₆F₃(SMe)₂, C₆F₄(SMe)₂, XC₆F₂(SMe)₃ and C₆F₂(SMe)₄. In some cases cleavage of the aromatic carbon-X bond (X = Br, I, CO₂H, SC₆F₅) forming C₆F₄(SMe)H and C₆F₂(SMe)₃H, and the O-Me bond forming HOC₆F₂(SMe)₃ was observed. The new compounds isolated have been characterized by elemental analyses, infrared and mass spectra and their stereochemistries have been from their ¹H and ¹⁹F NMR spectra.     

The thiolate anion as a nucleophile Part VII. Reactions of some fluorinated anilines and phenylhydrazines

Direct nucleophilic substitution with sodium methanethiolate of the fluorinated anilines and phenylhydrazines, pentafluorophenylaniline, the three isomeric tetrafluoroanilines, pentafluorophenylhydrazine, and 2,3,5,6-tetrafluorophenylhydrazine, gave replacement of one or two fluorine atoms. The new compounds isolated have been characterized by elemental analysis, infrared and mass spectra and their stereochemistries have been deduced from their NMR spectra (¹H, ¹⁹F and, in one instance, ¹³C).     

The thiolate anion as a nucleophile part X. Reactions of some nitrofluoroaromatics

The reactions of various nitrofluorobenzenes, C₆H_xF_yNO₂, with sodium methanethiolate have been studied in ethylene glycol/pyridine mixture as solvent. All the fluorine atoms, but not the nitrogroups, could be substituted by the methylthio group. The reactions have also been studied with the addition of a deactivating group, either methyl or amino, on the aromatic nucleus. Some of the methylthio groups in the products were oxidized to the corresponding sulfones. The new compounds isolated have been characterized and their spectra (IR, NMR and mass) examined.     

The thiolate anion as a nucleophile Part XI. Effect of the size of the nucleophile

The nucleophilic substitution reactions of some simple fluorobenzenes, C₆H_6?xF_x with sodium methanethiolates Na⁺SR^?(R=Et, $\text{i}$-Pr, $\text{t}$-Bu) have been studied. Some fully substituted products, C₆H_6?x(SR)_x, could be obtained in DMF as solvent with R = Et and $\text{i}$-Pr, but not when R = $\text{t}$-Bu. All the new products isolated have been characterized by elemental analysis, and NMR (H-1 and F-19), infrared and mass spectroscopy.     

Reactions of benzothiohydrazide as a bidentate nucleophile

Benzothiohydrazide acts as a 1,4-bidentate nucleophile under basic conditions, and condenses with suitably substituted pyridines, pyrimidines and quinoxalines to yield ring-fused-1,3,4-thiadiazines un-substituted on the 4-nitrogen position.     

Reactions of [aryloxy(phenyl)carbene]pentacarbonylchromium(0) complexes with thiolate ions. Decreasing reactivity with increasing basicity of the nucleophile

A kinetic study of the reactions of thiolate ions with three Fischer-type [aryloxy(phenyl)carbene]pentacarbonyl chromium(0) complexes in 50% MeCN-50% water (v/v) is reported. Br?nsted plots of the second-order rate constants are biphasic with an initial steep rise for weakly basic thiolate ions (beta(nuc) approximately equal to 1.0) followed by a slightly descending leg with a negative slope (beta(nuc) approximately equal to -0.2) for strongly basic thiolate ions. This indicates a change from rate-limiting leaving group departure at low pK(RSH)(a) to rate-limiting nucleophilic attachment at high pK(RSH)(a). The negative beta(nuc) values result from a combination of minimal progress of C-S bond formation at the transition state and the requirement for partial desolvation of the nucleophile before it enters the transition state. Possible factors that may affect the degree of bond formation in reactions of Fischer carbene complexes as well as reactions of other unsaturated electrophiles with thiolate ions are discussed.     

Reactions of Tin and Lead with Tricarbonylcyclopentadienylmolybdenum(II) and Tricarbonylcyclopentadienyltungsten(II) Chlorides

Tin was oxidized with tricarbonylcyclopentadienylmolybdenum and tricarbonylcyclopentadienyltungsten chlorides to obtain polynuclear organometallic compounds [⁵-C₅H₅M(CO)₃]₂SnCl₂ (M = Mo, W). The reactions of the above-mentioned oxidants with lead gave lead chloride and [⁵-C₅H₅M(CO)₃]₂ dimers. Formal-kinetic regularities of tin oxidation with tricarbonylcyclopentadienylmolybdenum chloride in N,N-dimethylformamide were found. Thermodynamic parameters of adsorption of the reagent on the metal surface were determined.     

The solvated fluoride anion can be a good nucleophile

Computations show how the solvated fluoride ion can be a good nucleophile in spite of its high solvation energy.     

Cycloisomerization of 1,6-enynes using acetate as a nucleophile under palladium(II) catalysis

[reaction: see text] An efficient method for the synthesis of five-membered carbo- and heterocyclic compounds, including fused rings, was reported using acetate as a nucleophile in the cyclization of 1,6-enynes under palladium(II) catalysis. The reaction is initiated by trans-acetoxypalladation of the alkynes and quenched by either trans- or cis-deacetoxypalladation in the presence of 2,2'-bipyridine as the ligand. An example of the catalytic asymmetric cyclization is presented with moderate enantioselectivity using chiral bisoxazoline ligand.     

Reactions involving fluoride ion. Part XII. Reactions of polyfluoro-aromatic compounds with octafluorobut-2-ene

Octafluorobut-2-ene is much more difficult to dimerise, with fluoride ion, than is hexafluoropropene but perfluoro-3,4-dimethylhex-3-ene is obtained under more forcing conditions. In contrast, polyfluoroalkylations with octafluorobut-2-ene are very efficient and results with perfluoro-pyridine, -pyridazine, and -quinoline are described, giving various perfluoro-2-butyl derivatives. Reactions with nitropentafluorobenzene and perfluorotoluene are also described. The ¹⁹F n.m.r. spectra of perfluoro-2-butylaromatic compounds reveal restricted rotation, even at room temperature.     

Oxygenation of a ruthenium(II) thiolate to a ruthenium(II) sulfinate proceeds via ruthenium(III)

Exposure of acetonitrile/methanol solutions of [PPN][Ru(DPPBT)3] [PPN = bis(triphenylphosphoranylidene); DPPBT = 2-diphenylphosphinobenzene thiolate] to oxygen initiates metal-centered oxidation, yielding the ruthenium(III) thiolate Ru(DPPBT)3. Ru(DPPBT)3 further reacts with oxygen, at sulfur, to give the ruthenium(III) sulfinate complex [Ru(DPPBT-O2)2(DPPBT)], which is reduced under ambient conditions to [PPN][Ru(DPPBT-O2)2(DPPBT)]. Ruthenium(II) sulfinate is the only product isolated from acetonitrile/methanol. Yellow crystals of [PPN][Ru(DPPBT-O2)2(DPPBT)] were obtained. Ruthenium(III) sulfinate was isolated as green prism-shaped crystals upon oxygenation of [PPN][Ru(DPPBT)3] in chlorobenzene/hexane. Electrochemical oxidation of ruthenium(II) sulfinate yields the ruthenium(III) derivative, which is rapidly reduced back to ruthenium(II) upon the addition of hydroxide.     

Some reactions of copper(I) pentafluorothiophenolate as a nucleophile

Several aromatic compounds containing one or two C₆F₅S groups have been prepared by nucleophilic displacement reactions using CuSC₆F₅ in DMF solution. Aromatic iodine or bromine, rather than chlorine of fluorine is replaced by the SC₆F₅ group using CuSC₆F₅. A mechanism is postulated. New compounds prepared include $\text{p}$-(C₆F₆F₅S)₂C₆H₄, $\text{o}$- and $\text{m}$-(C₆F₅S)₂C₆F₄ and $\text{p}$XC₆H₄SC₆F₅(X=C1, NO₂, I, CH₃, CO₂C₂H₅).     

Reactions of carbonate radical anion with amino-carboxylate complexes of manganese(II) and iron(III)

Abstract

The reaction kinetics of eight amino-carboxylate complexes of Fe(III) and Mn(II) with carbonate radical anion were studied using the pulse radiolysis method and UV-vis spectroscopy. Difference spectra revealed the formation of Fe(IV) and Mn(III) after reaction with CO₃^??. Spectral measurements revealed the first step to be the coordination of carbonate to the metal center. All of these led to the conclusion that the role of coordinated carbonate is essential to the electron transfer process by carbonate radical anion.