The chemistry of homogeneous transition metal systems offer parallels to the reactions on the surfaces of industrial hydrodesulphurization catalysts. The reactions of several ruthenium complexes with sulphur-containing reagents are described, with an emphasis on the kinetics and mechanisms thereof. The complex Ru(CO)₂(PPh₃)₃ (2), for example, reacts quickly with thiols and disulphides, producing cct-RuH(SR)(CO)₂(PPh₃)₂ (9) and cct-Ru(SR)₂(CO)₂(PPh₃)₂ (14), respectively, although 2 fails to react with unstrained thioethers. Reactions of the related complex Ru(CO)₂(PPh₃)(dpm) (dpm=Ph₂PCH₂PPh₂) are complicated by the lability of all of the three different ligands. The two dihydrides cct-RuH₂(CO)₂(PPh₃)₂ (3) and RuH₂(dpm)₂, as a cis/trans mixture (7), react with thiols to produce the hydrido-thiolato complexes 9 and RuH(SR)(dpm)₂ (13). respectively. The mechanisms appear to depend on the basicity of the hydride ligands; the more basic dihydride, 7, is probably protonated by the thiol, giving an unobserved molecular hydrogen intermediate, while 3 reacts by slow reductive elimination of H₂. The same rate constant, rate law, and activation parameters are found for the reaction of 3 with thiols, CO or PPh₃. The reaction of 3 with RSSR produces mostly 9, with small amounts of 14. The complete characterization of several members of the series 9 and 14 is described, including the crystal structure of the p-thiocresolate example of each. The reactions of 9 with other thiols, P(C₆H₄pCH₃)₃, CO, RSSR, HCl, PPh₃, and H₂, are also reported. The first three of these reactions share the same rate law and rate constant, the common rate determining step probably being initial loss of PPh₃. Some equilibrium constants for the exchange reactions of 9d (R=CH₂CH₃) with other thiols were tetermined, the Keq values increasing with the acidity of the incoming thiol. The mercapto hydrogens of 9a and 14a (R=H) exchange with the acidic deuterons of added CD₃OD. The hydridic and ortho-phenyl hydrogens exchange more slowly, presumably by intramolecular processes. Complex 14b (R=C₆H₄pCH₃) is unstable in the presence of light, exchanges phosphines rapidly with added P(C₆H₄pCH₃)₃, exchanges thiolate groups with added thiols, and is converted by high pressures of H₂ to a mixture of 9b and 3. Intermediates proposed for the mechanism of the thiol exchange reactions of 9 and 14 contain two or three thiolate groups sharing a proton. A related complex, [Ru(CO)₂(PPh₃)(μSEt)₂(μ₃SEt)Na(THF)]₂, which contains three thiolate groups on a ruthenium centre sharing a sodium cation, was isolated from the reaction of cct-RuCl₂(CO)₂(PPh₃)₂ with sodium ethanethiolate. In acetone, 9b and 14b can be formed cleanly from cct-RuHCl(CO)₂(PPh₃)₂ and cct-RuCl₂(CO)₂(PPh₃)₂, respectively, by reaction with p-thiocresolate. Complex 3 or cheaper analogues could be used as catalysts for the reduction of disulphides by H₂, or as recyclable reagents for the non-oxidative extraction of thiols from thiol-containing mixtures such as oil fractions. The chemistry described above will help to guide future researchers to systems that more closely parallel the processes occurring on the surfaces of industrial hydrodesulphurization catalysts. / Science, Faculty of / Chemistry, Department of / Graduate

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The purpose of this investigation is threefold: (1) to examine in detail the cycloaddition of halogenated ketenes and carbonyl compounds, (2) to study the decarboxylation of the resulting halogenated 2-oxetanones,and (3) to investigate the effect of halogens in the halogenated 2-oxetanones on the nucleophilic addition reaction.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1981. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 45-49. / by Mark Joseph Lupo. / M.S.

The compound Ru⁺²(CO)₃Cl₂(THF) spontaneously adsorbs onto MgO, Al₂O₃, SiO₂, and NaY zeolite from THF solution evolving less than 0.1 equivalent of CO to yield a light yellow supported complex. Based on reaction stoichiometry, CO evolution and in situ infrared spectroscopy, the adsorption was found to produce two different surface-bound species depending on the support used. On SiO₂ and NaY zeolite, the surface species Ru⁺²(CO)₃Cl₂(SURFACE) is formed by a ligand substitution of THF for a surface hydroxyl group. When the adsorption is performed on MgO or AI₂O₃, the inorganic oxide acts as a chloride acceptor to form the surface species Ru⁺²(CO)₃(SURFACE)₃. A molecular analog of the adsorbed species Ru(CO)₃Cl₂(SURFACE) was synthesized and characterized by infrared spectroscopy, ¹H NMR, and an X-ray crystal structure. The infrared spectra of the adsorbed species, Ru(CO)₃Cl₂(SURFACE), and the model compound were in close agreement. Model compounds of Ru(CO)₃(SURFACE)₃ were also synthesized: however, these could not be structurally characterized. The reactivity of the adsorbed species, Ru(CO)₃Cl₂(SURFACE) and Ru(CO)₃(SURFACE)₃, towards the formation of supported bimetallics, polynuclear ruthenium carbonyl clusters, and ruthenium bipyridine coordination compounds was investigated. On SiO₂ and NaY zeolite, the chemistry of Ru(CO)₃Cl₂(SURFACE) paralleled that of Ru(CO)₃Cl₂(THF) in solution. On Al₂O₃ and MgO, the chemistry of Ru(CO)₃(SURFACE), was indicative of an adsorbed ruthenium carbonyl-containing no chloride ligands. The bimetallic cluster RuCo₃(CO)₁₂⁻ was synthesized on hydroxylated Al₂O₃ by the disproportionation of RuCo₂(CO)₁₁. The trimeric cluster RuCo₂(CO)₁₁ is spontaneously adsorbed onto AI₂O₃ from a pentane solution yielding the adsorbed species "RuCo₂(CO)₁₀", this was then transformed to the tetrameric cluster RuCo₃(CO)₁₂⁻ by the addition of THF. The adsorbed cluster anion RuCo₃(CO)₁₂⁻ could also be synthesized on AI₂O₃ by the deprotonation of the hydridic cluster HRuCo₃(CO)₁₂. Depending on the route, infrared evidence suggests formation of a solvated or unsolvated anion on the surface. / Ph. D.