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 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 XII. Reactions of Lead(II) Benzenethiolate

The reactions of various fluoroaromatics, C₆F_6?xH_x, and C₆F₅X (X = C₆F₆, Cl, Me, NO₂, CF₃, COCl, CH₂Br, OMe, and NH₂) with lead(II) benzenethiolate in DMF have been examined. Lead thiolate acted as an excellent source of benzenethiolate anions and displacement of fluorine, chlorine or the nitro group was observed. The new products have been characterized by elemental analysis, and NMR (H?1 and F?19), infrared and mass spectroscopy.     

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.     

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.     

Photochemical reduction of n-tosylsulfilimines with thiolate anion

The reaction between N-tosyldiarylsulfilimines and p-toluenethiolate anion did not take place in the dark even upon heating up to 62° but proceeded smoothly upon irradiation with visible light in DMF at room temperature, affording S-N bond cleavage products.     

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 thiolate anions with 2-substituted-2-nitropropanes

Thiolates undergo substitution reactions with 2-substituted-2-nitropropanes by an S_RN1 mechanism or are oxidised to disulphides by an ionic mechanism.     

Dihydropyridazines. III . Reactions with oxygen

The reactions of oxygen with a series of dihydropyridazines have been explored. The primary reaction other than aromatization appears to occur from the 1, 4-dihydro tautomer. A single crystal x-ray structure has been determined on the product from the reaction of oxygen with 3, 6-diphenyl-4, 4-dimethyl-1, 4-dihydropyridazine.     

Reactions of a methylmercury zwitterionic thiolate complex [MeHg(Tab)]PF6 with various donor ligands: relevance to methylmercury detoxification

Reaction of MeHgI with Ag(2)O in H(2)O followed by addition of equimolar TabHPF(6) in MeCN gave rise to a methylmercury zwitterionic thiolate complex [MeHg(Tab)]PF(6) (1) (TabH = 4-(trimethylammonio)benzenethiol) in a high yield. Treatment of 1 with KI and KSCN afforded an anion exchange product [MeHg(Tab)]I·0.25H(2)O (2·0.25H(2)O) and [MeHg(Tab)]SCN (3), respectively, while that of 1 with equimolar Tab resulted in the formation of another MeHg/Tab compound [MeHg(Tab)(2)]PF(6) (4). The cation of 2 or 3 shows an approximately linear structure in which the central Hg(II) is coordinated by one C atom of one CH(3) group and one S atom of a Tab ligand. The Hg(ii) center of the cation of 4 is trigonally coordinated by one C atom of the CH(3) group and two S atoms of two Tab ligands. The analogous reaction of 1 with NH(4)SCN led to the cleavage of the Hg-C bond of 1 and the formation of a known four-coordinated Hg(II)/Tab complex [Hg(Tab)(2)(SCN)(2)] (5). When 4 was treated with 4,6-Me(2)pymSH or EtSH, another four-coordinated Hg(II)/Tab complex [Hg(Tab)(4)](3)(PF(6))(6) (6) was generated in a high yield. The Hg(II) center of each cation of 6 is tetrahedrally coordinated by four S atoms of four Tab ligands. The results suggested that cleavage of the Hg-C bond in the methylmercury complex 1 could be completed by increasing the coordination number of its Hg(II) center by S-donor ligands and protonating the methyl group by weak acids.