1,2-Ethanedithiol reacts with Pt(PPh3)4, Pd(PPh3)4, and Ni(PPh3)4 to give a monomer Pt(SCH2CH2S)2(PPh3)2, dimer Pd2(SCH2CH2S)4(PPh3) 2, and a dimer or polymer, respectively. The same compound can be obtained by treating the appropriate dihalo compound with 1,2-ethanedithiol in base. The palladium dimer cleaves with PMe2Ph to give Pd(SCH2CH2S)2(PMe2Ph)2. Monomers Pd(SCH2CH2S)2(diars) and Ni(SCH2CH2S)2(diphos) are obtained when the corresponding dichlorides are treated with 1,2-ethanedithiol. The addition of EtSH to Pt(PPh3)4 gives the unstable compound PtH(SEt)(PPh3)2. 2-(Methylthio)ethanethiol reacts with Pt(PPh3)4 to give the stable compound PtH(SCH2CH2SMe)(PPh3). The difference in stoichiometry and stability is a consequence of the chelate effect. With Pd(PPh3)4 and MeSCH2CH2SH the product is the dimer obtained from 1,2-ethanedithiol and has arisen from a demethylation reaction. With Ni(PPh3)4 the nonchelated Ni(SCH2CH2SMe)2(PPh3)2 is formed. Dimethyl disulfide does not react with Pt(PPh3)4 but (MeSCH2CH2S)2 readily gives Pt(SCH2CH2SMe)2(PPh3). This compound has one free and one coordinated 5-methyl group, and its formation is a further example of chelate assisted addition. With Pd(PPh3)4 all the phosphines are displaced, and a polymer, [Pd(SCH2CH2SMe)2]n, is obtained. The polysulfides Me2S3 and Me2S4 react with Pt(PPh3)4 to give Pt(SMe)2(PPh3)2. Reaction sequences are presented and the palladium demethylation reaction is discussed with respect to its relevance to the Raney nickel desulfurization.
ASJC Scopus subject areas
- Colloid and Surface Chemistry