Hydrogenation, Hydrogenolysis, and Desulfurization of Thiophenes by Soluble Metal Complexes:  Recent Achievements and Future Directions

Abstract

Petroleum and natural gas contain various organosulfur compounds, and their removal by hydrodesulfurization (HDS) over heterogeneous catalysts (eq 1) produces hydrocarbons and H 2 S, 1 which may be disposed of as elemental sulfur by the Claus process. 2Claudio Bianchini was born in Reggello, Italy, in 1949. After receiving his Ph.D. degree in chemistry from the University of Florence in 1973, he joined the Chemistry Department as a bourse-holder . He then moved to the pharmaceutical industry A. Menarini in Florence (1976-77) as a research officer. At the end of 1977, he became a researcher at ISSECC-CNR. Currently he is the Executive Director of ISSECC-CNR. His main research interests are in the field of homogeneous and liquid biphase catalysis and organometallic chemistry.(1)Chart 1

Syntheses and Fluxional Processes of Diphenyl(2‐thienyl)phosphane Derivatives of Triosmium Clusters

“…Two diphenyl(2-thienyl)phosphane ligands occupy equatorial coordination sites on Os(1) and Os (2) [28] In agreement with previous studies indicating that the presence of a tertiary phosphane ligand tends to lengthen the cis-OsOs bond in [Os 3 (CO) 11 (phosphane)] clusters, [29,30] some www.eurjic.org (27) 1.820(6) 3 ] there is no change of Os-Os bond lengths that can be related to the presence of two phosphane ligands. [31] The Os(1)-P(1) (2.343 Å) and Os(2)-P(2) [2.333(2) Å] distances are normal and close to those reported for [Os 3 -(CO) 10 (PPh 3 ) 2 ].…”

“…[25,26] Compound 3 crystallises with two independent molecules, which are conformational isomers (vide infra), in the asymmetric unit. The molecular structure of 3 is similar to that of previously characterised trisubstituted complexes of the general formula [M 3 (CO) 9 (phosphane) 3 ] [M = Os, Ru and phosphane = PMe 2 (CH 2 Ph), PMe 2 Ph, PPh(OMe) 2 , P(OEt) 3 , P(OCH 2 CF 3 ) 3 and PPh 3 ]. [31] The molecular structure of one of the two crystallographically independent molecules of 3 is shown in Figure 3; selected bond lengths and angles are listed in Table 2.…”

Iron(II) and Manganese(II) Complexes of 2-{2-(3-Carboxypyridin-2-yl)disulfanyl}pyridine-3-carboxylic acid Through C–S Bond Cleavage

“…There are numerous examples of metal complexes that catalytically cleave carbon-sulphur bonds [10][11][12][13][14][15][16][17][18][19][20]. However, only limited numbers of such reactions are used in synthesis of stable metal complexes [16][17][18][19][20].…”

C–S Bond Activation and Partial Hydrogenation of Thiophene by a Dinuclear Trihydride Platinum Complex

“…The evident importance of HDS together with environmental regulations that dictate increasingly smaller amounts of sulfur in gasoline and gasoil fuels [9,10] account for the current interest in developing more efficient technologies. Several reviews of the results obtained in the search for new heterogeneous catalysts, [11][12][13][14][15] in homogeneous modeling studies with transition-metal complexes [1,2,4,[16][17][18] and in computational stud- ies dealing with several aspects of heterogeneous HDS, [19][20][21][22][23] have already appeared. Remarkably, despite the large number of studies, the mechanism for the heterogeneous HDS of thiophenic molecules is not completely known and current technology has been unsuccessful in treating these compounds to achieve the sulfur levels required by new legislation.…”

“…[35] While the completely desulfurized hydrocarbons were obtained from the three heterocycles, the amount of desulfurization in the case of T was about 4 %. Overall, the notion that two metal centers might be required for cleavage of both thiophenic C-S bonds, [16] the high HDS activity shown by platinum metals, [48,49] and the fact that a polyhydride complex already contains the hydrogen needed for thiophene hydrogenolysis led us to explore the reaction of [(dppp) 2 Pt 2 H 3 ]-ClO 4 [dppp = 1,3-bis(diphenylphosphanyl)propane] with T and the mechanism of this reaction. Within the context of its possible relevance in the modeling of HDS studies, we first investigated the reactivity of [(dppp) 2 Pt 2 H 3 ]ClO 4 toward sulfur-containing species such as Na 2 S or NaSH.…”