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Platinum Metals Rev., 1982, 26, (2), 87

ABSTRACTS: April 1982

of current literature on the platinum metals and their alloys

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PROPERTIES


Chemistry of Acetylene on Platinum(111) and (100) Surfaces


e. l. muetterties, m. c. tsai and s. r. kelemen, Proc. Natl. Acad. Sci. U.S.A., 1981, 78, (11), 6571–6575

An ultra high vacuum study of acetylene chemisorption on Pt(111) and Pt(100) and of the reaction of H2 with the acetylene adsorbate has established distinguishing features of the C-H bond breaking and making processes as functions of pressure, temperature and surface crystallography. The rates for both processes are higher on the Pt(100) surface.

Coarsening Kinetics of Alloy Platinum-Palladium Particles on Oxide Substrates


r. w. clark, p. wynblatt and j. k. tien, Acta Metall., 1982, 30, (1), 139–146

The coarsening of small (5 nm initial radius) Pt-50at.%Pd particles supported on flat Al2O3 substrates was studied between 600 and 900°C under oxidising conditions. Particles or agglomerations of PdO were present in addition to the alloy particles after heat treatments at 600 and 700°C. Interparticle transport of PtO2 oxide molecules appears to control the rate of coarsening at 800 and 900°C. At 600 and 700°C the inherent rates of interparticle transport of both alloy components are the same.

Permeability of Hydrogen Isotopes through Pd-25wt.%Ag Alloy Membrane at Comparatively High Pressure and Temperature


h. yoshida, t. shimizu, y. matsuda and y. naruse, Japan Atomic Energy Research Inst., Tokai, Ibaraki, JAERI-M-9677, Sept. 1981

Permeation data in Pd-25wt.%Ag alloy for H2 and D2 were determined at high pressures (120−1300kPa) and temperatures 653–853K to aid design for the purification system in a fusion reactor fuel circulation system. The permeabilities obeyed Sievert’s law.

Thermoelectric Power of Palladium-Iron Alloys at Millikelvin Temperatures


d. i. bradley, a. m. guÉnaut, v. keith, g. r. pickett and w. p. pratt, J. Low Temp. Phys., 1981, 45, (3/4), 357–371

The thermoelectric power S of a pure Pd sample and four Pd-Fe alloys containing 77–400 ppm Fe was measured at temperatures down to 5mK. A sign change in S is observed at low temperatures in all the alloys consistent with the onset of spin-glass freezing, the cross over temperature varying as the square of Fe concentration. These alloys could be used as secondary thermometers down to at least 5mK.

Thermodynamics of Solutions of Hydrogen in Palladium-Manganese Alloys. II. Pd to PdMn


r. c. phutela and o. j. kleppa, J. Chem. Phys., 1982, 76, (3), 1525–1534

The thermodynamic properties of dilute solutions of H2 in Pd−50at.% Mn alloys were studied by a combined calorimetric equilibrium method at 555−909K. The results showed that for alloys up to 25at.% Mn the enthalpies of solution become increasingly negative with increasing Mn content. The changes are due to increased occupation by H atoms at higher temperatures of energetically less favourable sites.

On the Reduction in Magnetization by Cold Working on the Ferromagnetic Heusler Alloy Pd2MnSn


t. shinohara, k. sasaki, h. yamauchi, h. watanabe, h. sekizawa and t. okada, J. Phys. Soc. Jpn., 1981, 50, (9), 2904–2908

X-ray, magnetic and Mossbauer effect measurements were made on cold worked Pd2MnSn. They show a remarkable reduction in magnetisation. Most of the reduced magnetisation is recovered when the strain is released by annealing the specimens at temperatures below 400°C where no appreciable recovery of the chemical order takes place.

Thermal Stability of Pd2Si and PdSi in Thin Film and in Bulk Diffusion Couples


k. n. tu, J. Appl. Phys., 1982, 53, (1), 428–432

Thermal stability of films of Pd2Si and PdSi formed on (III) Si wafer were studied by X-ray diffraction. Pd2Si transformed to PdSi at 810±10°C and PdSi transformed back to Pd2Si when annealed below that temperature. It is concluded that Pd2Si rather than PdSi was the thermodynamically stable phase on Si at low temperature, contrary to the phase diagram.

Resistivity and Temperature Coefficient of Resistivity of Ruthenium Oxide Layers. Influence of Morphology


g. lodi, c. de asmundis, s. ardizzone, e. sivieri and s. trasatti, Surf. Technol., 1981, 14, (4), 335–343

RuO2 layers 1−2μ m thick were prepared at 300, 400, 500 and 600°C on quartz supports by two different procedures which caused “cracked” and “compact” films. The films were characterised by chemical composition, crystalline structure and resistivity, ρ, and Differences in ρ and at constant chemical composition were attributed to film discontinuities at the grain boundaries. No metal-semiconductor transition was observed from 20−150°C and the electrical and electrocatalytic properties of the non-stoichiometric layers do not appear to be directly related.

Oxidation of Tertiary Polycyclic Amines by RuO4


g. bettoni, g. carbonara, c. franchini and v. tortorella, Tetrahedron, 1981, 39, (24), 4159–4164

The reactions of certain tertiary polycyclic amines with RuO4 in heterogeneous and homogeneous systems have established an order of reactivity for various methylene groups adjacent to the N, with respect to this oxidising agent.

CHEMICAL COMPOUNDS


Synthesis of Bis(cis -dichloro(diamine) platinum(II)) Complexes with Variable Bridges and Study of Their Binding with Poly (dA-dT) by Melting Profiles


i.-b. paek, p. a. snyder-robinson and b.-k. teo, Inorg. Chem., 1981, 20, (11), 4006–4009

The synthesis of a series of new bis(cis -dichloro(diamine)Pt(II)) complexes with a variable and flexible bridge is reported. Their reactions with synthetic DNA, poly(dA-dT) were investigated to find the effects of the bridging chain length on their binding to DNA. Their anti-tumour activity is related to their ability to interact with DNA.

Mixed Palladium-Platinum Complexes with Ph2PCH2PPh2(dppm)


p. g. pringle and b. l. shaw, J. Chem. Soc., Chem. Commun., 1982, (1), 81–82

The first mixed Pd-Pt complexes with bis-(diphenylphosphino)methane (dppm), together with their “A-frame” adducts with CO, SO2 and MeOOCC ≡ CCOOMe are described. The complexes were characterised by elemental analysis (C, H, N and halogen), molecular weight determinations, i.r. spectroscopy and 31P 1H, 1H and 1H 31P NMR spectroscopy.

Fluorosulfates of the Noble Metals. Part 4. Fluorosulfates of Iridium


k. c. lee and f. aubke, J. Fluorine Chem., 1982, 19, (3–6), 501–516

The synthesis of the binary fluorosulphates Ir(SO3F)3 and Ir(SO3F)4 and of the ternary fluorosulphates (ClO2)2[Ir(SO3F)6], Cs2[Ir(SO3F)6] and Ba[Ir(SO3F)6] is described. Structural characterisations are based on i.r. spectra and, in the case of the Ir(IV) compounds, on the temperature dependant magnetic susceptibility measurements.

Synthesis and Properties of Substituted Ruthenium Aqua Complexes


p. bernhard, h. lehmann and h. ludi, J. Chem. Soc., Chem. Commun., 1981, (23), 1216–1217

[Ru(H2O)6]2+ was prepared and then found to be a versatile reagent for the easy synthesis of a variety of complexes [Ru(H2O)nL6−n]2+(L = heterocyclic N-donor), whose spectroscopic and electrochemical properties are described.

ELECTROCHEMISTRY


Behaviour of Hydrogen Peroxide on Platinum Anode


n. ia. kravchenko, v. g. formichev and g. a. cheryshev, Zh. Prikl. Khim. (Leningrad), 1981, 54, (12), 2675–2680

Studies of anodic oxidation of H2O2 at potentials 1.0−1.7V were performed on a rotating Pt anode electrode in 0.5M H2SO4 at electrolyte temperature of 20 ± 0.1°C. The reaction formed PtO, O2 and H2O, with the rates of reaction depending on H2O2 concentration and energy of O-metal bond, but did not depend on the potential. H2O2 acted as an activator for the surface oxidation and a passivator for the multi-reduction.

Oxygen Evolution on Tantalum-Polypyrrole-Platinum Anodes


g. cooper, r. noufi, a. j. frank and a. j. nozik, Nature, 1982, 295, (5850), 578–580

Polypyrrole films were used as protective coating on Ta metal photoanodes to find if the films could protect the electrodes for self oxidation during O2 evolution. The polypyrrole was stable in the presence of O2, and was a poor electrocatalyst for O2 evolution. Pt can be deposited on its surface to enhance O2 evolution. Ta-polypyrrole-Pt electrode structures were found to be indistinguishable from naked Pt electrodes for O2 evolution.

Electrocatalytic Oxidation of Methanol on Platinum Based Binary Electrodes


b. beden, f. kadirgan, c. lamy and j. m. leger, J. Electroanal. Chem. Interfacial Electrochem., 1981, 127, (1–3), 75–85

Four Pt-based binary catalysts (Pt + Sn, Pt + Pb, Pt + Re, Pt + Ru) used for the electrochemical oxidation of methanol were studied by linear and cyclic voltammetry. Except for the Pt + Ru system, which always gives increased electrocatalytic activity, the other ad-atom + Pt systems showed increased activity for some concentration ranges of the precursor salts, and for some ranges of electrode potential. In general the three ad-atoms behave as relatively strong catalytic poisons.

Selective Electro-Oxidation of Carbon Monoxide with Carbon-Supported Rh-and Ir-Porphyrins at Low Potentials in Acid Electrolyte


j. f. van baar, j. a. r. van veen and n. de wit, Electrochim. Acta., 1982, 27, (1), 57–59

Studies of C supported Group VIII metalloporphyrins as O2 reduction electrocatalysts showed that catalysts based on Rh and Ir are very active in the electrochemical oxidation of CO, particularly when pretreated at high temperatures in an inert atmosphere. The Rh and Ir porphyrin-Norit BRX catalysts have the unique feature of selectively oxidising the CO component of carbon monoxidehydrogen gas mixtures.

Mechanism of Saturated Hydrocarbon Oxidation in Aqueous Solutions of Ru(IV) Chloride Complexes. II. Oxidation of Alkanes by Strong Oxidants in the Presence of Ru(IV) Complexes


l. n. arzamaskova, a. v. romanenko and iu. i. ermakov, Kinet. Katal., 1981, 22, (6), 1438–1445

Alkanes C3-C4 were easily oxidised in aqueous solutions of Ru(IV) chloride complexes under mild conditions (77·5°C) by strong oxidisers [IrCl6]2−, , Cl2 and S2O82−. The rate of oxidation of alkanes was determined by the value of the oxidative-reductive potential of the oxidiser. A reaction mechanism is presented.

PHOTOCONVERSION


The Photochemical Decomposition of Sulphuric Acid Catalysed by [HPt(PEt3)3]


r. f. jones and d. j. cole-hamilton, J. Chem. Soc., Chem. Commun., 1981, (24), 1245–1246

Far u.v. irradiation of Pt(PEt3)3 in dilute H2SO4 promoted cyclic photolysis, resulting in H2 and probably also persulphate ions. This eliminates problems associated with back reactions in multi-component intermolecular electron transfer processes. There are no problems with concentration quenching and much higher catalyst concentrations can be used than for multicomponent catalysts. O2 can be released from the persulphate ion in a subsequent step, giving a simple way of separating O2 and H2. Both H2 and S2O82− production are favoured by low pH.

Studies of Photoeffects on a Pt-Electrode under Laser Irradiation


a. v. gorodyskii, g. ia. kolbasov, i. v. sekirin and n. i. taranenko, Ukr. Khim. Zh. (Russ. Ed.), 1981, 47, (11), 1170–1174

Studies of photoeffects on a Pt electrode were performed during laser irradiation in H2SO4 and iodide ions. Laser irradiation of the Pt electrode by light of wavelength λ ≥ 0.337μ m results in photodecomposition of surface oxides and changes in the electrocatalytic properties of Pt in relation to the formation of chemisorbed H2 and O2.

Efficiency of Some Platinum Catalysts in the Photochemical Water Reduction


m. maestri and d. sandrini, Nouv. J. Chim., 1981, 5, (12), 637–641

A comparison of Pt catalyst efficiency and the effect of Pt concentration on the rate of H2 evolution was studied in the photochemical cycle for H2 production from H2O. H2 production increased with increasing Pt concentration and reached a plateau whose value was different for the various catalysts. Low H2 production is due to low catalyst efficiency and low quenching efficiency leading to free MV+.

The Characterization and Behavior of Catalysts Prepared by Heterogeneous Photodeposition Techniques


w. w. dunn and a. j. bard, Nouv. J. Chim., 1981, 5, (12), 651–655

Pt and Pd were deposited on TiO2 from an aqueous solution containing the metal salt and acetate, by a photodeposition process. The catalysts were characterised and their activities were compared for the solution phase hydrogenation of benzene with commercial Pt/Al2O3 and Pt black catalysts. Photooxidation of oxalic acid was also investigated.

Photocatalytic Hydrogen Production from Aliphatic Alcohols over a Bifunctional Platinum on Titanium Dioxide Catalyst


p. pichat, j.-m. herrmann, j. disdier, h. courbon and m.-n. mozzanega, Nouv. J. Chim., 1981, 5, (12), 627–636

Photocatalytic H2 production from linear C1-C4 primary aliphatic alcohols and from propan-2-ol was studied at room temperature using a 4.85wt.%Pt/anatase catalyst in liquid or gas phase static photoreaction. Over u.v. illuminated TiO2, H2 formation was limited, and the surface was progressively reduced. Quantum yields were ∼ 0.45 for CH3OH, ∼ 0.2 for C2H5OH and ∼ 0.1 for other alcohols. H2 production from liquid H2O under the same conditions was at least 4 orders of magnitude less than from liquid methanol. The dehydrogenations correspond to a chemical storage of light energy.

The Photocatalytic Dehydrogenation of 2-Propanol by Using RhCl(PPh3)3


h. arakawa and y. sugi, Chem. Lett., 1981, (9), 1323–1326

RhCl(PPh3)3 catalyses the dehydrogenation of 2-propanol under photo-irradiation from a Hg lamp at room temperature. The catalytic activity of the reaction mixture is very high.

LABORATORY APPARATUS AND TECHNIQUE


Transition Metal-Gate MOS Gaseous Detectors


t. l. poteat and b. lalevic, IEEE Trans. Electron Devices, 1982, ED-29, (1), 123–129

MOS capacitors with gates of Pd, Pt and Ni are sensitive detectors of H2, CH4, C4H10 and CO. 1MHz and 10Hz C-V characteristics change by −1240 and −215mV when the Pd-gate MOS capacitor is exposed to H2 at 760 and 2 × 10−8 torr, respectively. Pt-gate MOS capacitors show half the change of Pd-gate devices. Pd-gate devices absorb H2 in 190−200ms at 760 torr H2, but need 200 min to reach 63% of the total change at 2 × 10−8 torr H2. Pt- and Ni-gate devices are slower than Pd. The detection is attributed to work function change.

HETEROGENEOUS CATALYSIS


Interaction of Carbon Monoxide with Supported Platinum Catalyst


g. a. savel’eva, t. k. galeev, n. m. popova, v. f. vozdvizhenskii and v. m. mishchenko, Kinet. Katal., 1981, 22, (5), 1253–1259

Thermal desorption and spectroscopic studies were performed on the CO interaction with 0.5−5wt.%Pt/γ -Al2O3 catalysts. The CO adsorbed in three different forms corresponding to temperature intervals of desorption: 25−250°C (I), 250−700°C (II) and 550−850°C (III). During CO adsorption in the first two forms, the metal and substrate participate. The adsorption during the third form, however occurs on oxidised Pt centres forming stable carbonyl structures. Increasing temperature leads to CO adsorption in forms II and III.

Platinum-Tin Reforming Catalysts. 1. The Oxidation State of Tin and the Interaction between Platinum and Tin


r. burch, J. Catal., 1981, 71, (2), 348–359

Two series of bimetallic 0.3wt.% Pt-0.3−5wt.% Sn/Al2O3 catalysts were prepared by the impregnation of samples of industrial Pt/Al2O3 reforming catalysts with solutions of Sn(IV) chloride in acetone. Chemisorption shows that the amount of H2 adsorbed by Pt is increased when Sn is present. This indicates that Sn increases the dispersion of the Pt. It is concluded that Sn is stabilised in the Sn(II) state by interaction with the support and consequently, that no proper Pt-Sn alloys are formed in these catalysts.

Hydrogenation of Nitrogen Oxide on Platinum-Carbon Catalysts in Acidic Medium


i. paseka, Collect. Czech. Chem. Commun., 1982, 46, (11), 2669–2675

Studies of the hydrogenation of NO in acidic solution over Pt/C catalysts showed it to be dependent on the experimental conditions either in the purely diffusion region, or in the diffusion and kinetically controlled region. The boundary between these two processes moves to the higher ratio of NO : H2 partial pressure with increasing Pt content and decreasing agitation.

Oscillatory Behavior of Metallic Honeycomb Catalysts


v. hlavacek and j. rathouskÝ, Chem. Eng. Sci., 1982, 37, (3), 375–380

Measurements of catalyst temperature and outlet conversion on a metal honeycomb system performed on a catalyst made of a thin layer of α -Al2O3 deposited on a metal honeycomb matrix impregnated by Pd showed that the CO oxidation may proceed chaotically in time over a range of inlet CO concentrations and temperatures. For higher inlet temperatures, chaotic oscillations become more “symmetrical” and finally disappear. The effect of surface memory was observed for 1% CO.

Amination of Phenols with Ammonia over Palladium Supported on Alumina


y. ono and h. ishida, J. Catal., 1981, 72, (1), 121–128

The amination of phenol with NH3 in the presence of H2 over Pd/Al2O3 gives aniline at 250°C. The rate determining step is the hydrogenation of phenol into cyclohexanone. The catalytic behaviour of Pd is improved by making an alloy with Au or by co-supporting with La3+ or Al3+ ions.

Catalytic Properties of PdCl2.CuCl2/Zeolite Systems in the Oxidation of C2-C4 Olefins to Carbonyl Compounds


kh. m. minachev, n. ia. usachev, a. p. rodin and ia. i. isakov, Izv. Akad. Nauk SSSR, Ser. Khim., 1982, (1), 132–136

Studies of the catalytic behaviour of the PdCl2.CuCl2/zeolite system obtained by saturation were made during oxidation of C2-C4 olefins into carbonyl compounds. Activity, selectivity and stability of the synthetic faujasite systems exceed that of PdCl2. CuCl2 Al2O3 (SiO2, amorphic aluminosilicate) and also that of ion exchanged PdCu/zeolites. Conditions for obtaining 98−99% selective conversion of C2H4 in acetaldehyde and C3H6 in acetone are given.

Transition Metal Templates for Selectivity in Organic Synthesis


b. m. trost, Pure Appl. Chem., 1981, 53, (12), 2357–2370

Pd templates offer new ways of selectivity during organic syntheses. These are shown in four problems during allylic alkylation: chemoselectivity, regioselectivity, stereocontrol and enantioselectivity. For instance, Pd initiated cyclisations exhibit a remarkable degree of control of ring size not available in non-transition metals.

Analysis of Mechanism of Ethylene Hydrogenation by Hydrogen Permeating Palladium Membrane


h. nagamoto and h. inoue, J. Chem. Eng. Jpn., 1981, 14, (5), 377–382

A hydrogenation reactor with a Pd catalytic membrane permeated by H2 was used for ethylene hydrogenation. There were two ethylene partial pressure regions, one where the overall reaction rate is ∼ proportional to ethylene partial pressure, the other where the overall rate equals the permeation rate of H2 into a vacuum at constant H2 pressure.

Air Stability of Catalysts Derived from Osmium and Ruthenium Cluster Carbonyls


d. j. hunt, d. jackson, r. b. moyes, p. b. wells and r. whyman, J. Chem. Soc., Chem. Commun., 1982, (1), 85–86

Supported Os and Ru cluster carbonyl catalysts Os6(CO)18, Os6(CO)12 and Ru(CO)12 impregnated on Al2O3, SiO2 and TiO2 were found to retain their activity after exposure to air.

Hydrogenation of Benzene to Cyclohexene on an Unsupported Ruthenium Catalyst. Effect of Poisons


c. u. i. odenbrand and s. t. lundin, J. Chem. Tech. Biotechnol., 1981, 31, (11), 660–669

Studies of the effect of poisoning of Ru catalysts on the selective hydrogenation of benzene to cyclohexene showed the yield and the rate of hydrogenation to be greatly affected by the degree of poisoning. A reproducible catalyst was prepared by precipitating the catalyst precursor, as the hydroxide, in a glass vessel at 353K. An optimum H2 pressure for maximum yield was obtained.

Ammonia Synthesis on Ruthenium Powder from 100 to 500°C and Hydrogenation of Preadsorbed Nitrogen down to − 70°C


g. rambeau and h. amariglio, J. Catal., 1981, 72, (1), 1–11

Kinetic analysis of NH3 synthesis over Ru shows the reaction rate is inversely proportional to H2 pressure and directly proportional to N2 pressure, so the reaction is limited by N2 adsorption and inhibited by H2. NH3 production has been observed down to − 70°C. Hydrogenating the preadsorbed N2 allows the N2 coverage and rate of N2 chemisorption on the bare surface to be measured. The latter indicates that the intrinsic catalytic activity of Ru is 500 to 2000 times higher than that of Fe between 400 and 250°C.

HOMOGENEOUS CATALYSIS


Dimerisation of a Diplatinum to a Tetraplatinum Complex during Catalysis of the Water Gas Shift Reaction: the X-Ray Crystal Structure of [Pt4(μ 2 − CO)2 (μ 2-Ph2PCH2PPh2)3{Ph2PCH2P(:O)Ph2}]


a. a. frew, r. h. mill, l. manojloviĆ-muir, k. w. muir and r. j. puddephatt, J. Chem. Soc., Chem. Commun., 1982, (3), 198–200

The binuclear complex [Pt2H2(μ -H)(μ -dppm)2][PF6], dppm = Ph2PCH2PPh2, is an active catalyst precursor for the water gas shift reaction, especially at low CO pressures. The catalytic solution contains cluster complexes such as tetranuclear [Pt4(μ -CO)2(μ -dppm)3{Ph2PCH2P(:O)Ph2}].

Catalytic Activity of Some Palladium Complexes during Oligomerisation of Isoprene in Protone Solvents


r. berger, v. gaube and iu. n. kukushkin, Khim. Khim. Tekhnol., 1982, 24, (10), 1291–1293

The systems based on sulphinate Pd complexes K[Pd(C6H5SO2)2(H2O)Cl] and salicylaniline Pd complexes [Pd(OC6H4CH = NC6H5)2] in the presence of phosphines and in alcohol media catalysed both the dimerisation and telomerisation of isoprene. The catalytic activity was equal to that of acetylacetonate based Pd systems.

Palladium Catalysis in Natural Product Synthesis


j. tsuji, Pure Appl. Chem., 1981, 53, (12), 2371–2378

A review of new syntheses for natural products, mostly steroids, based on Pd-catalysed reactions is presented. (23 Refs.)

Kinetic Investigations of the Synthesis of Acetic Anhydride by Homogeneous Catalysis


m. schrod and g. luft, Ind. Eng. Chem., Prod. Res. Dev., 1981, 20, (4), 649–653

A kinetic study of the carbonylation of methyl acetate to acetic anhydride over a catalyst system including RhCl3 hydrate, methyl iodide, an organic base and Cr compounds was made at CO pressures of 5–75 bar and at 165−205°C. The reaction rate was independent of the CO pressure above 15 bar and did not depend on methyl acetate concentration. The reaction was first order for Rh, methyl iodide and the base, if its concentration was low. With rising base concentration the order of reaction decreased.

A Study of the Mechanism of Rhodium Phosphine-Catalysed Hydroformylation: Use of 1,1-′Bis(diarylphosphino) ferrocene Ligands


j. d. unruh and j. r. christenson, J. Mol. Catal., 1982, 14, (1), 19–34

Rh phosphine-catalysed hydroformylation was studied using 1,1-′bis(diphenylphosphino)ferrocene and several derivatives containing substituents on the phenyl groups (p -Cl, m -F and p -CF3). The most selective catalyst has three P atoms bound to each Rh atom and is postulated to be a diRh complex. It is confirmed that the linear : branched ratio increases as ligand basicity decreases.

Oxidation of Alcohols by Transition Metal Complexes—IV. The Rhodium Catalysed Synthesis of Esters from Aldehydes and Alcohols


r. grigg, t. r. b. mitchell and s. sutthivaiyakit, Tetrahedron, 1981, 37, (24), 4313–4319

Both RhH(CO)(PPh3)3 and a catalyst made in situ from RhCl3.3H2O, PPh3 and Na2CO3 catalyse the reaction of aldehyde with simple primary alcohols to give esters, together with alcohols formed from aldehyde reduction. The proportion of ester can be increased by adding an efficient hydrogen acceptor.

Catalysis of the Water Gas Shift Reaction by Complexes of Rhodium and Iridium with 2,2′-Bipyridine and Similar Ligands


p. a. marnot, r. r. ruppert and j.-p. sauvage, Nouv. J. Chim., 1981, 5, (11), 543–545

The water gas shift reaction is efficiently catalysed under mild temperature (< 100°C), pressure (1 atm) and pH in water by soluble complexes of Rh and Ir. Turnover frequencies > 50/hour have been obtained at 100°C, pH around neutrality under 1 atm CO.

Bimetallic Catalysts from Pseudotetrahedral Iridium-Tungsten Clusters. Syntheses and Crystal Structures of (η 5-C5H5)WIr3(CO)11 and (η 5-C5H5)2W2Ir2(CO)10


j. r. shapley, s. j. hardwick, d. s. foost, g. d. stucky, m. r. churchili., c. bueno and j. p. hutchinson, J. Am. Chem. Soc., 1981, 103, (24), 7383–7385

Convenient syntheses and molecular structures of two tetranuclear Ir-W clusters CpWIr3(CO)11 (1) and Cp2W2Ir2(CO)12 (2) (Cp = η 5-C5H5) and their use as precursors to Al2O3-supported bimetallic catalysts are reported during hydrogenolysis of n-butene. The [Ir4] catalyst had high selectivity for scission of the central C-C bond in butane, forming two molecules of ethane. The [WIr3] and [2W2 + Ir4] catalysts showed ethane selectivity of 70% or greater, but the [W2Ir2] catalyst had < 50% ethane in the product stream.

Carboxylic Acids from Syngas


j. f. knifton, Hydrocarbon Process., 1981, 60, (12), 113–117

A new route for preparing short-chain aliphatic carboxylic acids using homogeneous Ru and Rh catalysts, where the products may be based optionally upon syngas feedstocks alone, is described. Lower molecular weight carboxylic acids are homologised by synthesis gas in the presence of a solubilised Ru or Rh species plus a suitable I-containing promoter. Catalysts such as RuO2, H4Rh4(CO)12, Ru3(CO)12, Ru(acac)3, RuCl3, RuCl2(PPh3)3, Rh(acac)3, Rh2O3, RhCl3, Pd(OAc)2-8PPh3 are used. Catalyst selection, operating conditions, the homologation reaction, process description, and costs are described.

Ru-Catalyzed Oxidation of Acetylene to α -Diketones with Iodosylbenzene


p. mÜller and j. godoy, Helv. Chim. Acta., 1981, 64, (8), 2531–2533

Disubstituted acetylenes are oxidised with PhIO in the presence of RuCl2(PPh3)3 to give α -diketones in 65−85% yield. Under the same conditions terminal acetylenes are cleaved to carboxylic acids.

ELECTRICAL AND ELECTRONIC ENGINEERING


Pd-Thin-SiO2-Si Diode. I. Isothermal Variation of H2-Induced Interfacial Trapping States. II. Theoretical Modelling and the H2 Response


b. keramati and j. n. zemel, J. Appl. Phys., 1982, 53, (2), 1091–1099, 1100–1109

The current-voltage characteristic and the small-signal frequency dependent admittance response of a Pd-thin-SiO2-Si diode were measured. A method was developed to calculate the d.c. response and the small signal admittance of a MIS diode under a given applied voltage. The generated interfacial trapping states were responsible for the induced electrical changes in the Pd-thin-SiO2-Si diodes.

Anodic Evolution of Oxygen on Sputtered Iridium Oxide Films


s. hackwood, l. m. schiavone, w. c. dautremontsmith and g. beni, J. Electrochem. Soc., 1981, 128, (12), 2569–2573

The catalytic properties of sputtered Ir oxide films (SIROF’S) in acidic electrolytes were studied. Long term stability is demonstrated. Typical steady state currents are 75mA/cm2 at 1.85V, which is 50% higher than previously reported. The high current density and absence of corrosion demonstrate the superior catalytic properties of SIROF’s vs . Ir over the entire voltage range studied.

MEDICAL USES


Carcinostatic Effect of a Caffeine-8-Ether-Platinum Complex


h. krÖger and j. klosa, Naturwissenschaften, 1981, 68, (12), 628

The caffeine-8-ether-Pt complex (Cofplatin) was synthesised and given to rats and mice with various sarcomas, when cessation in growth in the tumours was seen. Cofplatin is a stable non-aggressive substance and further research is being done.

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