Tapani Venäläinen

Mode of formation of polymeric [{Ru(bipy)(CO)2}n](bipy = 2,2′-bipyridine) films

Electrochemical generation of the organometallic polymer [{Ru0(bipy)(CO)2}n] by reduction of [RuII(trans-Cl2)(bipy)(CO)2] proceeded via the formation of the corresponding dimer [{RuI(trans-Cl)(bipy)(CO)2}2] and a tetrameric species; only dimers were formed by electroreduction of the [RuII(cis-Cl2)(bipy)(CO)2] isomer or [RuIICl(bipy){cis-(CO)2}(CO2Me)].

Chemically activated ruthenium mono(bipyridine)/SiO2 catalysts in water–gas shift reaction

Abstract Chemical activation of supported ruthenium mono(bipyridine) carbonyls was found to be an effective route to highly active water–gas shift catalysts. Catalysts were activated by treating silica supported [Ru(bpy)(CO)2Cl2], [Ru(bpy)(CO)2ClH], [Ru(bpy)(CO)2Cl(C(O)OCH3)] or [{Ru(bpy)(CO)2Cl}2] with dilute NaOH or KOH solution. Ruthenium mono(bipyridine) carbonyls were deposited onto the support by impregnation from organic solvent or by pulse impregnation technique. In a typical experiment, catalysts achieved the final activity during WGS reaction. This induction period could be reduced by carrying out the hydroxide treatment under CO atmosphere. Catalytic activity was tested in the continuous flow WGS reaction at the temperature range 100–170°C. The non-activated supported complexes showed at most moderate activity. Chemical treatment with NaOH or KOH solution increased the turnover frequency at the whole temperature range. The highest activities were obtained with NaOH treated [{Ru(bpy)(CO)2Cl}2]/SiO2, which gave turnover frequencies as high as 14 500 (mol CO2 (Ru mol)−1 (24 h)−1) at 150 °C.

Ligand substitution of FeRu2(CO)12 and Fe2Ru(CO)12 with tertiary phosphines and phosphites

Abstract Ligand substitution of the mixed-metal clusters FeRu 2 (CO) 12 and Fe 2 Ru(CO) 12 with triphenylphosphine and trimethylphosphite has been studied. Mono- and di-substituted derivatives have been synthesized and characterized structurally. The following crystal and molecular structures are reported: Fe 2 Ru(CO) 11 PPh 3 : triclinic, space group P 1 , a 9.203(2), b 11.903(3), c 15.117(4) A, α 81.54(2), β 87.28(2), γ 66.72(2)°, Z = 2; Fe 2 Ru(CO) 11 P(OMe) 3 : orthorhombic, space group Pna2 1 , a 17.220(5), b 14.572(4), c 8.708(6) A, Z = 4, FeRu 2 (CO) 11 PPh 3 : monoclinic, space group P2 1 /n , a 11.435(3), b 16.034(5), c 16.642(4) A, β 93.35(2)°, Z = 4; FeRu 2 (CO) 10 (PPh 3 ) 2 : orthorhombic, space group Pccm , a 14.854(4), b 17.180(7), c 16.786(12) A, Z = 4. Ligand substitution is found to occur preferentially at the ruthenium centers of the FeRu 2 and Fe 2 Ru clusters. Monosubstitution causes expansion of both of the clusters while the overall geometry is practically unchanged. Disubstitution of FeRu 2 (CO) 12 causes contraction of the cluster and leads to a formation of carbonyl bridges. The structural trends have been interpreted in terms of electronic and packing effects of ligand substitution. The X-ray structures of Fe 2 Ru(CO) 12 and FeRu 2 (CO) 12 are not known; the ligand substitution studies indicate that Fe 2 Ru(CO) 12 has the same structure as Fe 3 (CO) 12 , and that FeRu 3 (CO) 12 does not have a Ru 3 (CO) 12 structure as postulated previously from the IR studies.

Studies on the synergetic effect of group viii transition metal carbonyls on homogeneous catalysis of the water-gas shift reaction

Abstract Homogeneous catalysis of the water-gas shift reaction by Group VIII mixed metal carbonyls and by mixtures of Group VIII metal carbonyls in pyridine solution was examined under mild conditions (T= 100°C, P co = 0.42–0.60 atm). A weak synergetic effect of Group VIII metals was observed between iron and iridium carbonyls. A stronger synergetic behaviour of mixed metal Fe/Ru catalyst precursors (Fe2Ru(CO)12 and FeRu2(CO)12) was noted. The effect of phosphine and phosphite substitution on Fe2Ru(CO)12 and FeRu2(CO)12 was examined. Only monosubstitution on Fe2Ru(CO)12 was found to have an enhancing effect on catalytic activity. Rhodium carbonyls, which were found to produce the most active catalyst solution under homogeneous water-gas shift conditions, did not show a synergetic behaviour with other Group VIII metals.

Mixed metal clusters: structural and reactivity trends

Abstract The results from a systematic synthesis and trends in structural and physical properties and chemical reactivity for a large group of clusters are valuable for the understanding of the role of a particular element in a mixed metal cluster. As an example tetrahedral HxM4(CO)12 clusters, where M represents metals Fe, Ru, Co and Rh or their combinations, are discussed in detail. Their metalmetal bond distances and 1H NMR parameters are presented as a function of metal composition. Similar trends are also shown for their reactivity towards phosphine substitution.

Ligand substitution of Ru3(CO)12 with 2,2'-bipyridine (bipy). X-Ray crystal structure of Ru3(CO)10(bipy)

The reaction of Ru3(CO)12 with 2,2′-bipyridine (bipy) in hexane gives in high yield Ru3(CO)10(bipy), containing two asymmetrically bridging carbonyl groups trans-to the perpendicularly co-ordinated bipyridine ligand.

A new synthetic route to mixed-metal clusters Fe2Ru(CO)12 and H2Fe2Ru2(CO)13. A crystal structure study of H2Fe2Ru2(CO)13

Summary The reaction of [Ru(CO) 3 Cl 2 ] 2 and [Fe(CO) 4 2− ] in water solution gives the mixed-metal clusters Fe 2 Ru(CO) 12 , H 2 Fe 2 Ru 2 (CO) 13 and variable amounts of H 2 FeRu 3 (CO) 13 . The reaction provides a practical route to H 2 Fe 2 Ru 2 (CO) 13 . Structural and spectroscopic studies reveals that H 2 Fe 2 Ru 2 (CO) 13 crystallises together with H 2 FeRu 3 (CO) 13 in the space group C 2/ c , the average structure closely resembling that of pure H 2 FeRu 3 (CO) 13 . The 1 H NMR spectrum shows the fluxionality of H 2 Fe 2 Ru 2 (CO) 13 and provides a convenient method of analysis of the cluster mixture.

Dispersion relations for evaluating the complex refractive index of medium without the information of its thickness

A general method to obtain the complex refractive index of a medium from absorbance, or alternatively from optical path length data, without knowing the sample thickness is proposed. The method can be formulated in any spectral range and it is here applied particularly in the terahertz spectral range to both simulated and experimental data. The key idea is the derivation of nonconventional dispersion relations that partly resemble traditional Kramers-Kronig relations. The method is shown to work well in extracting the complex refractive index of a drug system and a precipitated calcium carbonate.

The reactivity of ruthenium mono(bipyridine) carbonyl complexes in an alcoholic solution of alkali metal carbonates

Abstract Chlorine containing ruthenium bipyridine carbonyl compounds react readily in dilute alkaline solutions under a CO atmosphere affording a poorly soluble and air sensitive product that is suggested to have a polymeric nature. Various analysis methods (MS and TPD) were used in the characterisation of the product. The replacement of the axial chloride ligands in trans(Cl), cis(CO)[Ru(bpy)(CO)2Cl2] and [Ru(bpy)(CO)2Cl]2 is proposed to be the initial step in the polymerisation. The replacement of chlorides in methanolic solution was confirmed by isolating and characterising the dimeric intermediate [Ru(bpy)(CO)2(COOCH3)]2.

FT-IR studies on the catalyst Ru3(CO)12/2,2′-bipyridine/SiO2 and related ruthenium-bipyridine surface complexes

Abstract The influence of the preparation method and conditions on the highly active, supported catalyst Ru 3 (CO) 12 /2,2′-bipyridine/SiO 2 was studied by diffuse reflectance FT-IR spectroscopy. Two liquid-phase methods, impregnation from organic solvent and pulse impregnation, and an atomic layer epitaxy (ALE)-derived gas-phase method were applied in the catalyst preparation. In all preparation methods the surface reaction proceeded via physisorbed [Ru 3 (CO) 12 ] and 2,2′-bipyridine. Irrespective of the method employed, the original cluster [Ru 3 (CO) 12 ] was lost during activation and new ruthenium monobipyridine surface species were formed. The solvent played a critical role in the liquid-phase methods. Use of chlorinated solvents such as dichloromethane favoured the formation of the less active chlorinated surface species [{Ru(bpy)(CO) 2 Cl m } n ]3SiO 2 ( m = 1, 2 and n ⩾ 1), whereas use of non-chlorinated solvents or the gas-phase method gave rise to more active [{Ru(bpy)(CO) 2 } n ]/SiO 2 ( n ⩾ 1). Supported mononuclear [Ru(bpy)(CO) 2 Cl 2 ], [Ru(bpy)(CO) 2 Cl(C(O)OCH 2 ] and [Ru(bpy)(CO) 2 ClH] complexes proved to be useful model compounds for the [Ru 3 (CO) 12 /2,2′-bipyridine/SiO 2 catalyst yielding similar IR patterns to those of [{Ru(bpy)(CO) 2 Cl m } n ]/SiO 2 .