Alan R. Sanger

Hydroformylation of 1-hexene catalysed by complexes of rhodium(I) with DI- or tritertiary phosphines

Abstract The addition of a small amount of a di- or tritertiaryphosphine to a solution of [RhH(CO) (PPh3)3] in benzene enhances the hydroformylation activity and selectivity of the system, but addition of an amount exceeding equimolar reduces the activity of the system. Equilibrium mixtures of terti- aryphosphine—rhodium complexes, with different degrees of substitution, of different catalytic activity are postulated to explain these observations.

The structures and hydroformylation catalytic activities of polyphosphine complexes of rhodium(i), and related complexes-immobilised on polymer supports

Abstract The structures and the hydroformylation catalytic activity of complexes of rhodium(I) with di- or triphosphines, or with tertiary phosphine anchorsites on polymers, have been studied. Substitution of one PPh 3 ligand of the parent complex, RhH(CO) 2 (PPh 3 ) 2 , by one phosphine group of a di- or triphosphine gives a bridged complex of higher catalytic activity than the parent complex, but substitution for all PPhs ligands gives a complex of lower activity. Immobilisation of Rh I at phosphine anchor-sites on polymeric supports gives square—planar or trigonal—bipyramidal complexes in which Rh I is coordinated to one or a maximum of two anchor-sites. The square—planar bis-(phosphine) complexes are normally trans . The structures adopted by these systems depend upon (a) the separation between anchor-sites, and (b) the flexibility of the side-chain containing the anchor-site. Polymeric supports containing the following anchor-sites have been investigated:

Catalytic wet air oxidation in the presence of hydrogen peroxide

Abstract Wet air oxidation of chlorophenols has been examined at a range of temperatures (60-200°C), with and without added hydrogen peroxide, and in the presence or absence of a series of catalysts containing oxides of Mn, Cu, or Fe, alone or supported on SiO 2 or Al 2 O 3 . In the absence of hydrogen peroxide Mn-containing catalysts are effective, at higher temperatures. In the presence of hydrogen peroxide catalysts containing each metal are effective, and at lower temperatures.

Formation of an asymmetric RhHgRh bridged complex

Abstract Reaction of HgCl2 with [Rh2(μ-Cl)(CO)2(μ-CO)(μ-dppm)2]Cl (dppm = bis(diphenylphosphino)methane) gives [Rh2Cl3(μ-HgCl)(CO)2(μ-dppm)2] in which only one Rh is oxidised by insertion into a HgCl bond, and which consequently contains an unusual asymmetric RhHgRh bridge.

Ruthenium complexes containing Ph2PCH2CH2SPh as a mono- or bidentate ligand or both

Abstract Reaction of [RuCl 2 (CO) 3 ] 2 with Ph 2 PCH 2 CH 2 SPh ( L ) gives successively [RuCl 2 (CO) 3 ( L )] and [RuCl 2 (CO) 2 ( L ) 2 ], in each of which L is coordinated by the phosphorus atom alone. In contrast, the complexes [RuCl 3 ( L )], and [RuCl 2 ( L ) 2 ] each contain L as a bidentate ligand. The complex [RuCl 2 (CO)( L ) 2 ] contains L as both a monodentate and a bidentate chelating ligand.

FeCrO Nanoparticles as Anode Catalyst for Ethane Proton Conducting Fuel Cell Reactors to Coproduce Ethylene and Electricity

Ethylene and electrical power are cogenerated in fuel cell reactors with FeCr2O4 nanoparticles as anode catalyst, La0.7Sr0.3FeO3-𝛿 (LSF) as cathode material, and BaCe0.7Zr0.1Y0.2O3-𝛿 (BCZY) perovskite oxide as proton-conducting ceramic electrolyte. FeCr2O4, BCZY and LSF are synthesized by a sol-gel combustion method. The power density increases from 70 to 240 mW cm−2, and the ethylene yield increases from about 14.1% to 39.7% when the operating temperature of the proton-conducting fuel cell reactor increases from 650∘C to 750∘C. The FeCr2O4 anode catalyst exhibits better catalytic performance than nanosized Cr2O3 anode catalyst.

Hydrogenation and Hydroformylation Reactions Using Binuclear Diphosphine-Bridged Complexes of Rhodium

Modification of transition-metal complexes by complexation with Lewisbase ligands, especially phosphines or phosphites, has led to major improvements in catalytic reactivity and selectivity.(1,2) Further, by permitting operation of production facilities at more moderate temperatures and pressures, considerable reductions in both capital and operating costs have been realized. For example, this is true of recent installations for the production of butyraldehyde using rhodium hydroformylation catalysts.(3,4) The majority of industrial hydrogenation reactions are performed using heterogeneous catalysts.(5) Nevertheless, the homogeneous hydrogenation catalysts are of importance for laboratory-scale reactions, the synthesis of thermally unstable or otherwise sensitive products (especially those of biological interest), applications of prochiral catalysts for the production of optically-active products, notably L-dopa (see Chapter 4), and mechanistic studies.(1,2,6,7)

Preparation of a Rh-SnCl2-Rh bridged A-frame complex, and the reversible reaction with CO and chloride to form the corresponding SnCl3− complex

Abstract Reaction of SnCl2·2H2O with [Rh2Cl2(CO)2(μ-dppm)2] occurs to form [Rh2(μ-Cl)(μ-SnCl2)(CO)2(μ-dppm)2]Cl. Reaction of this complex with CO causes a sequence of reactions resulting in the displacement of the tin ligand and the formation of [Rh2(μ-Cl)(CO)2(μ-CO)(μ-dppm)2][SnCl3].

Dinuclear Complexes of Rhodium as Catalysts For the Reactions of Alkenes with Carbon Monoxide and Hydrogen

SUMMARY Neutral or cationic dinuclear complexes of rhodium(I), [Rh 2 X 2 (CO) (μ-Ph 2 -PCH 2 PPh 2 ) 2 ] or [Rh 2 (μ-YXCO) (μ-Ph 2 PCH 2 PPh 2 ) 2 ] + (X,Y=Cl,I,CN; n = 2–4) and related complexes, are efficient catalysts for the sequential hydrogenation of alkynes to alkenes and alkanes under an atmosphere of hydrogen alone. Under an atmosphere of hydrogen and carbon monoxide these catalysts are highly selective for hydrogenation of alkynes to alkenes. At elevated temperatures these complexes are also active for the hydroformylation of alkenes to aldehydes, ketones, cyclic ketones, or acetals. The product distribution is dependant upon the precise nature of the catalyst, the solvent, reaction temperature, and proportion of reagents. In methanol a sequence of reactions occurs in which the product aldehyde forms an acetal, ether, and finally a product containing a methylene group generated from the CO inserted in the hydroformylation reaction.