Thiolate substitutions

Electron Transfer from the Molecular to the Nanoscale Table 3 Energy gaps in thiolate-substituted gold clusters. ... 

No thiolate substitution of p-dichlorobenzene, 1,2,4,5-tetrachloro-benzene, or pentachlorophenylanisole in alcohol was observed Substitution of 2,3,4- and 2,4,5-trichlorobenzonitrile, 2,3-, 2,5- and 3-4-dichlorobenzonitrile and o- and p-chlorobenzonitriles with sodium hydrogen sulphide in liquid ammonia afforded the cyanothiophenols. Preferential replacement of the p-Cl was observed. Meto-chlorobenzo-nitrile did not undergo nucleophilic substitution under these conditions, but was rather hydrolysed by the water present in the NaSH . ... 

Simple thiolate substitution of an aliphatic compound can be represented by the equation... 

HIPIP). The rates of initial thiolate substitution in reactions of (11) (R = Et or Bu ) with arylthiols in acetonitrile solution have been reported/ and the mechanism shown in Scheme 3 is proposed for the ligand-exchange process (S represents a sulphide S in the Fe4Si core). 

Kinetic studies of thiolate substitution in alkyl (R = ethyl or tert-butyl) tetrameres dianions with arylthiols (R = XC6H4SH with X = P-NH2, P-CH3, P-NO2, 0-NO2) indicate that the rates are overall second order, first order in each tetramere and thiol. The most interesting feature of these kinetic studies is the dependence of rate constants on thiol acidity. This has led to the postulation of the mechanism illustrated in the scheme on Fig. 5.8. Here the slow protonation step should be followed by fast separation of the alkylthiol from and subsequent capturing of the generated arylthiolate anion by the metal center. 

Fig. 5.9. Thiolate substitution reaction in [Fc4S4SR4] species [Que Jr. L, Anglin JR, Bobrik MA, Davison A, Holm RH (1974) J. Am. Chem. Soc. 96 6042]...

Iron-proteins can themselves participate in thiolate substitution reactions. There are indeed two types of this kind of process, namely active center core extrusion and protein reconstitution. Both are related to displacement of the Fe-S core between the protein and an appropriate organic thiol ... 

Alkylthio- and arylthio-pyridazines can be prepared from the corresponding halo-substituted pyridazines by using appropriate alkyl and aryl thiolates. 

A thiol, usually under basic catalysis, can undergo Michael addition to an activated double bond, resulting in protection of the sulfhydryl group as a substituted S-ethyl derivative. Displacement of an ethyl tosylate by thiolate also affords an S-ethyl derivative. 

The hydrothiolation of terminal alkyl alkynes with 96 (Fig. 2.17) proceeds with good degree of regio- and chemo-selectivity, especially with thiophenol and p-methoxy-thiophenol as substrates. Isomerisation to the internal alkenyl thiolates accounts for less than 9% of the thiolated products under the reaction conditions. In addition, further hydrothiolation of the vinyl thioether product is not observed. Typical conversions of 70-85% at 1 mol% loading at 80°C within 5 h are observed. Arylthiols substituted with electron-withdrawing groups afford lower conversions. 

---