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The titanium complex [TiCp*(thiosal)(thiosalH)] (1) has been synthesised by reaction of [TiCp*Me3], Cp* = η5-C5Me5, with thiosalicylic acid (H2thiosal). Complex 1 reacts with [M(μ-OH)(COD)]2 (M = Rh, Ir) to yield the corresponding early–late heterobimetallic complexes [TiCp*(thiosal)2M(COD)] (M = Rh (2); Ir (3)). Carbon monoxide replaces the COD ligand in 2 and 3 leading to the respective dicarbonyl complexes [TiCp*(thiosal)2M(CO)2] (M = Rh (4); Ir (5)). Compound 4 reacts with PPh3 to yield the monocarbonyl derivative [TiCp*(thiosal)2Rh(CO)(PPh3)] (6). The reaction of compound 1 with LinBu yields the tetrametallic complex [{TiCp*(thiosal)2Li}2(THF)3(H2O)] (7). Compound 7 reacts with [RuCp*Cl(COD)] yielding the heterometallic complex [TiCp*(thiosal)2RuCp*] (8). The molecular structures of compounds 4, 5 and 7 have been studied by X-ray diffraction. From cyclic voltammetric (CV) and square wave voltammetric (SWV) experiments, we observed that attachment of the titanium moiety of precursor 1 to a late transition metal moiety through the sulfur atoms has a significant influence on the reduction behaviour of the Ti(IV) metal centre. Thus, monometallic 1 exhibits an irreversible reduction process at −1.15 V vs. SCE, whereas the CVs of heterobimetallic compounds 2–6 are characterized by the reversible or quasi-reversible one-electron reduction of the Ti(IV)/Ti(III) system, suggesting a significant stabilization of the Ti(III) reduced species. Likewise, substitution of the M(COD) diolefin fragment in 2 and 3 by the M(CO)2 carbonyl-containing moiety (in compounds 4 and 5) leads to a significant anodic shift in the titanium E1/2 reduction redox potentials.

The reaction of [TiCp*Cl3] with [Fe(η5-C5H5)(η5-C5H4COOH)] in the presence of NEt3 yields [TiCp*{(OOC–C5H4)FeCp}3] (1), (Cp = η5-C5H5). The alkyl complex [TiCp*Me3] reacts with [FeCp(η5-C5H4–CH2COOH)] or anthranilic acid rendering the tris-carboxylate titanium complexes [TiCp*{(OOCCH2–C5H4)FeCp}3] (2) and [TiCp*{(OOCC6H4NH2)3] (3), respectively. Complex 3 can be protonated with triflic acid to render [TiCp*{(OOCC6H4NH2)3].HOTf (4). The reaction of [TiCp*Me3] with anthranilic acid in a 1:2 M ratio yields the alkyl carboxylate derivative [TiCp*Me{(OOCC6H4NH2)2] (5). Complex 5 reacts with tBuNC to render the iminoacyl complex [TiCp*(η2-MeCNtBu){(OOCC6H4NH2)2] (6). The reaction of [TiCp*Cl3] with the ferroceneacetic acid, gives [TiCp*Cl2{(OOCCH2–C5H4)FeCp}] (7). The [TiCp*Cl]2(μ–O)[(ΟΟC–C5H4)2Fe] (8) can be obtained by reaction of [TiCp*Cl3] with [Fe(η5-C5H4–COOH)2] in the presence of a base. The molecular structures of 1 and 8 have been established by X-ray diffraction methods.

The synthesis of PtRu nanoparticles has been accomplished by using the dendrimer-encapsulated nanoparticle (DEN) approach. We report that the surface distribution of the particles can be tuned by suitable control of the reaction pathway. The present study focuses on the synthesis and characterization of Pt and PtRu nanoparticles and the evaluation of their performance as COad electro-oxidation catalysts. Bimetallic Pt/Ru particles displaying Ru-core Pt-shell (Ru@Pt) and Pt-core Ru-shell (Pt@Ru) structures, in which Ru or Pt are preferentially located on the outermost layer of the nanoparticles, have been synthesized. Characterization data confirm the formation of the bimetallic particles with the desired atomic distribution. The importance of the actual nature of the bimetallic samples in the COad electro-oxidation reaction has been discussed.

Quantitative determination of Zr in the system constituted by quartz microspheres functionalized with two kinds of organometallic compounds has been studied due to the importance of the correct quantization of the Zr from a catalytic point of view. Two parallel approximations were done, i.e. acid leaching and direct solid quantization. To validate the acid leaching TXRF measures, ICP-MS analysis were carried out. The results obtained by means of the optimization of the quantitative direct solid procedure show that, with a previous particle size distribution modification, TXRF obtain the same analytical results as ICP-MS and TXRF by acid leaching way but without previous chemical acid manipulation. This fact implies an important improvement for the analysis time, reagents costs and analysis facility and it proves again the versatility of TXRF to solve analytical problems in an easy, quick and accurate way. Additionally and for the direct solid TXRF measurements, a deeper study was done to evaluate the intrinsic analytical parameters of the Zr TXRF analysis of this material. So, the influence of the particle size distributions (modified by means of a high power ultrasound probe) with respect to uncertainty and detection limits for Zr were developed. The main analytical conclusion was the strong correlation between the average particle sizes and the TXRF analytical parameters of Zr measurements, i.e. concentration, accuracy, uncertainty and detection limits.

The influence of the structure and morphology of PtRu nanoparticles supported on functionalized carbon black has been investigated for CO and methanol electrooxidation in a half-cell and in a DMFC single cell. Carbon black was treated with HNO3 to obtain an oxidized surface (Vulcan-N), and PtRu nanoparticles supported on Vulcan-N were prepared via impregnation, Bonnemann's method and the sulfito-complex route. Temperature programmed reduction (TPR) measurements evidence the presence of RuO2·xH2O phase in the catalyst obtained by the sulfito-complex route. This phase was stabilized by metal–support interaction, whereas alloy characteristics were estimated for PtRu catalyst obtained by impregnation and Bonnemann's method. The nature of the precursor–support interaction, induced by the nature of the functional groups on the carbon surface, affects the structure of the electrocatalyst and subsequent behavior in electroactivity. When synthesized through Bonnemann's method, the surface oxygen-containing groups of the support seem to be unable to stabilize the anhydrous precursors of platinum and ruthenium, yielding crystalline RuO2. Methanol electrooxidation performance was clearly different in the three catalysts, whereas only a few negligible differences were observed in CO oxidation. The superior performance in DMFC of the catalysts obtained by the sulfito-complex route accounts for both the presence of RuO2·xH2O species and the functionalization of carbon black.

A series of new compounds has been synthesised from an electron-rich olefin derived from cyclam (A). Thus, A reacts with oxygen gas to give the syn-bis(urea) 1 and with sulfur to yield the anti-bis(thiourea) 2. The reaction of A with triflic acid furnishes the bis(imidazolium) triflate 3, which gives the monoprotonated imidazolium salt 4 upon treatment with sodium tetraphenylborate in water. Theoretical calculations (DFT) predict the diprotonated species to be energetically disfavoured, thus demonstrating the importance of hydrogen-bonding interactions. Treatment of compound 3 with silver oxide affords the di- and monoprotonated cationic salts 5a and 5b in THF and dichloromethane, respectively. The molecular structures of compounds 1, 2, 3, 4, 5a and 5b have been established by X-ray diffraction. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

The titanium complex [TiCp*(OSBz)(OBzSH)] (1) has been synthesized by reaction of [TiCp*(Me)3] (Cp* = η5-C5Me5) with 2-mercaptobenzyl alcohol (H2OSBz). The reaction of complex 1 with H2O gives the dinuclear oxo-bridged complex [{TiCp*(OSBz)}2(μ-O)] (2). Complex 1 reacts with [M(μ-OH)(cod)]2 (M = Rh, Ir) to yield the early–late heterobimetallic complexes [TiCp*(OSBz)2M(cod)] {M = Rh (3); Ir (4)}. Carbon monoxide easily replaces the cod ligand in 3 and 4, which leads to the corresponding dicarbonyl derivatives [TiCp*(OSBz)2M(CO)2] {M = Rh (5); Ir (6)}. Compound 5 reacts with PPh3 to yield the monocarbonyl complex [TiCp*(OSBz)2Rh(CO)(PPh3)] (7). The molecular structures of complexes 2 and 5 have been established by single-crystal X-ray diffraction studies. The structure of complex 1 and its coordination mode toward a rhodium moiety have been ascertained by means of calculations based on density functional theory. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

A series of new titanium pyridine−alkoxide complexes, [TiCp*Cl{2,6-(OCH2)2py-κ3-O,N,O}] (2), [TiCp*{2,6-(OCH2)py(CH2OH)-κ1-O}{2,6-(OCH2)2py-κ3-O,N,O}] (3), [TiCp*Me2{2-(OCH2)py-κ1-O}] (4), [TiCp*Me{2-(OCH2)py-κ1-O}2] (5), and [TiCp*(O){2-(OCH2)py-κ2-O,N})] (6), have been synthesized. All of these compounds were characterized by NMR spectroscopy. The single-crystal structures of [TiCp*Me{2,6-(OCH2)2py-κ3-O,N,O}] (1), 2, 3, and 4 were determined and revealed the presence of piano and nonpiano stool geometries. The molecular structures of 1, 2, and 3 were also studied by means of density functional theory (DFT) in an attempt to rationalize the possible reasons for the stabilization of one or other geometry., This work was supported by the Ministerio de Ciencia e Innovación (MCINN), Spain (Grant Nos. CTQ2005-08123-C02-01/BQU, CTQ2006-11845/BQU, and Consolider-Ingenio 2010 ORFEO CSD2007-00006) and the Junta de Comunidades de Castilla-La Mancha, Spain (Grant No. PCI08-0010).

A series of new tantalum-tbcp [tbcp = 2,2′-thiobis(4,6-dichlorophenolato)] and tantalum-tbop [tbop = 2,2′-thiobis(6-tert-octylphenolato)] complexes [TaCp*Cl2(κ3-tbop)] (1), [TaCp*Cl2(κ3-tbcp)] (2), [TaCp*Me2(κ3-tbop)] (3), [TaCp*Me2(κ3-tbcp)] (4), [TaCp*Me(κ3-tbop)(OTf)] (OTf = triflate) (5), [TaCp*Me(κ3-tbcp)(OTf)] (6), [TaCp*(κ3-tbop)(OTf)2] (7), and [TaCp*(κ3-tbcp)(OTf)2] (8) have been synthesized. Insertion processes into the methyl groups of complex 3 were not observed upon reaction with CO or isocyanides. In contrast, complex 4 reacted slowly with 1 equiv of xylyl isocyanide (xylyl = 2,6-dimethylphenyl) or tert-butyl isocyanide to yield complexes [TaCp*(κ2-Me2CNxylyl)(κ3-tbcp)] (9) and [TaCp*Me(κ2- MeCNtBu)(κ3-tbcp)] (10), respectively. All products were characterized by NMR spectroscopy and elemental analysis. The single-crystal structures of 2, 3, 6, and 9 were also determined.

The new tantalum siloxide complex [TaCp*Me3(OSiPh3)] (1; Cp* = η5-C5Me5) has been synthesized. The reaction of complex 1 with isocyanides yields the respective azatantalacyclopropanes [TaCp*(η2-Me2CNxylyl)Me(OSiPh3)] (2; xylyl = 2,6-dimethylphenyl) and [TaCp*(η2-Me2CNtBu)Me(OSiPh3)] (3). The molecular structure of complex 2 has been established by X-ray diffraction. Complex 2 reacts with a second mol-equiv. of 2,6-xylyl isocyanide to yield [TaCp*(Nxylyl)[N(xylyl)CMe=CMe2)(OSiPh3)] (4). The reaction of 1 with carbon monoxide gives [TaCp*(O)(OCMe=CMe2)(OSiPh3)] (5), whereas 1 reacts with B(C6F5)3 to give the corresponding cationic compound [TaCp*Me2(OSiPh3)][MeB(C6F5)3] (6). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Unpromoted and Ce-promoted Fe catalysts were tested in the CO2 hydrogenation reaction. Both catalysts form predominantly CO and hydrocarbons (C1–C10). Reaction rate and selectivity to the different products were essentially the same with both catalysts. The chain growth probability (α) was very similar in both cases (∼0.44). Prior of being used in the CO2 hydrogenation reaction, the catalysts were used in CO hydrogenation until the stationary state was established. It was found that the Ce incorporation into the iron catalyst does not alter its final performance but it shortens the time required to reach stationary-state operation conditions.

A series of carbon supported PtAu electrocatalysts has been prepared. The performance of the samples in the methanol oxidation reaction and in the oxygen reduction reaction has been investigated by means of electrochemical techniques. The combined process, oxygen reduction reaction in the presence of methanol, has also been studied by electrochemical methods and in a single-cell. Irrespective of the performance of the samples in the oxygen reduction reaction, the ones displaying poor activity in the methanol oxidation reaction are the optimum cathode electrocatalysts for direct methanol fuel cell applications. The role of Au was found to be dependent on the actual nature of the catalyst. When alloyed, the role of Au on the methanol oxidation reaction is negligible. This is the first time that Au is being proposed as a component of methanol resistant cathode electrocatalysts.

The performance of PtCo/C electrocatalysts in the oxygen reduction reaction is enhanced after thermal treatment in hydrogen. In fact, the intrinsic activity (per gram of Pt) of PtCo/C electrocatalyst after the adequate treatment is far superior to that of the commercial sample. The PtCo nanoparticles were prepared from the water-in-oil microemulsion technique. The total metal loading of the catalyst was 30 wt%, and two reduction temperatures, 300 and 875 8C, were studied. Electrochemical measurements were carried out using the rotating disk electrode method in 0.5 M H2SO4 at room temperature, while the Pt real surface area was determined by CO stripping voltammetry. Analyses from XPS and TPR revealed that the amount of Co and Pt reduced species as well as the particle size (XRD), increased with the thermal treatment. Results derived from the electrochemical analyses were in agreement with those obtained in a H2/O2 single cell. These results demonstrate the important role of the cobalt as well as the reduction temperature and atmosphere, and open new ways for the design of improved bimetallic catalyst. # 2007 Elsevier B.V. All rights reserved.

A mesoporous silica functionalized with octyl groups had been used as the support for lipase (from Candida antarctica ) immobilization. The hydrophobicity provided by the hydrocarbon chains together with the excellent morphologic characteristics of the solid leads to high enzyme loadings in monolayer fashion. However, in this kind of systems the aqueous enzyme solution cannot easily access all the inner surface of the pores because of the highly hydrophobic nature of these surfaces. Thus, the presence of low ethanol concentration decreases the hydrophobicity of the channels and the access of enzyme seems to be significantly improved. The monolayer capacity (400–500 mg protein/g of octyl silica) increases twice compared to the corresponding immobilization in the absence of ethanol (200 mg protein/g of octyl silica). The activity of the derivatives prepared in the presence of ethanol was also significantly improved: 33,000 tributyrin units/g of catalyst at the monolayer limit, which is four- to five-fold higher than the activities of the corresponding derivatives prepared in the absence of ethanol.

The heterometallic complex [TiCp*(O(2)Bz)(2)AlMe(2)] (2) has been synthesised by reaction of [TiCp*(O(2)Bz)(OBzOH)] (1) with AlMe(3) (Cp*=eta(5)-C(5)Me(5); Bz=benzyl). Complex 1 reacts with HOTf to yield the cationic derivative [TiCp*(OBzOH)(2)]OTf (3) (HOTf=HSO(3)CF(3)). Compound 3 reacts with [{M(mu-OH)(cod)}(2)] (M=Rh, Ir; cod=cyclooctadiene) to render the early-late heterometallic complexes [TiCp*(O(2)Bz)(2){M(cod)}(2)]OTf (M=Rh (4); Ir (5)). The molecular structure of complex 4 has been established by single-crystal X-ray diffraction studies.

Pt and Au are not miscible within a whole range of concentrations. To obtain PtAu alloys, severe thermal treatments are required that to provide aggregation phenomena. However, it is possible to synthesize bimetallic PtAu nanoparticles provided the proper synthesis route is employed. When they are prepared from water-in-oil microemulsions or with the impregnation technique, it is possible to obtain nanosized bimetallic PtAu particles. In contrast, other colloidal routes have been seen to be adequate for the synthesis of other bimetallic Pt-based particles, affording segregated samples with Pt- or Au-enriched zones. When alloyed, bimetallic PtAu nanoparticles display unique physicochemical properties that are different from those of monometallic and nonalloyed solids. Thus, the performance of alloyed PtAu samples as electrocatalysts for the oxygen reduction reaction is superior to that of the PtAu-segregated samples. In fact, the ability of carbon-supported bimetallic PtAu samples in the oxygen reduction r...

The new titanium guanidinido complexes [TiCp*Me2{(PhN)2CNH2}] (1), and [TiCp*Cl2- {(PhN)2CNH2}] (2) (Cp* = η5-C5Me5) have been synthesized. The reaction of complex 1 with [Rh(μ-OH)(cod)]2 affords the rhodium guanidinido complex [Rh{(PhNH)(PhN)CNH}(cod)]2 (3). The molecular structures of complexes 1 and 3 were studied by X-ray diffraction methods. Complex 3 can also be prepared by reaction of [Rh(μ-OH)(cod)]2 with N,N'-diphenylguanidine.

Two Fe–Ce catalysts were prepared by wet impregnation of Ce onto iron oxyhydroxide (FeOOH) and hematite iron oxide (α-Fe2O3), respectively. Their performance in the Fischer–Tropsch (FT) synthesis was investigated and compared with that obtained with a Ce-free α-Fe2O3 catalyst. It was observed that the behavior of the different catalysts changed along the course of the FT reaction. The catalysts were tested for different periods of time, carefully passivated, recovered from the reactor and characterized by different techniques. The FT activity of the Ce-loaded and Ce-free catalysts decreased initially, but at a certain point the catalytic activity started to increase. The time needed to reach this inflection point depended on the catalyst composition, being shorter for the Ce-promoted catalysts. The catalytic activity of the Ce-free catalyst increased when the Fe3C species were transformed into χ-Fe2.5C, which are suggested to be the carbide phase present when polymerized carbon species (Cβ) are formed. The addition of Ce to the iron oxyhydroxide developed solids with a higher BET surface area. Besides, these samples displayed a higher FT activity at long time-on-stream (TOS). Moreover, Ce addition also facilitated the formation of the Cβ species previous to the evolution of Fe3C into χ-Fe2.5C, and therefore, promoted the FT synthesis reaction.

Reaction of [Cp*TiMe3] with O(SiPh2OH)2 yields the titanium siloxide derivative [Cp*TiMe{(OSiPh2)2O}] (1). Complex 1 reacts with H2O to yield the corresponding oxo-titanium derivative [(Cp*Ti{(OSiPh2)2O})2(µ-O)] (2). The molecular structure of complex 2 has been established by X-ray diffraction. Complex 1 reacts with triphenylsilanol to give the asymmetric titanium siloxide [Cp*Ti(OSiPh3){(OSiPh2)2O}] (3). Treatment of the dinuclear titanium compound [(Cp*TiCl2)2(µ-O)] with an equimolar amount of O(SiPh2OH)2 yields complex [(Cp*TiCl)2{µ-(OSiPh2)2O}(µ-O)] (4) in which the disiloxide moiety is bridging two titanium atoms. The structure of 4 has been determined by X-ray diffraction. Reaction of [Cp*TiMe3] with HOSiPh3 yields the titanium triphenylsiloxide [Cp*TiMe2(OSiPh3)] (5). Complex 5 reacts with water to yield [{Cp*TiMe(OSiPh3)}2(µ-O)] (6). The triflate compound [Cp*Ti(OSiPh3)2(OTf)] (7) can be prepared by reaction of 5 with HOTf and triphenylsilanol. We have tested the catalytic activity of some of the complexes in the epoxidation of cyclohexene.

The electrocatalytic behaviour of PtRu/C is modified by the addition of nickel. Results from X-ray photoelectron spectroscopy reveal that the amount of surface Ni is less than the expected from the bulk stoichiometry, especially in the used samples where Ni was not detected. The oxidation state of Ni plays a key role on the catalytic performance of PtRuNi/C electrocatalysts, particularly in the CO oxidation reaction due to the development of Pt–Ni electronic interaction. The influence of the nature of the carbon support was also evaluated. Electrocatalysts prepared on a carbon-modified substrate displayed higher activities in the methanol oxidation reaction than those prepared over non-treated carbon. For the Ni-containing samples, the preparation route determines the degree of interaction between Pt and Ni of the different samples and hence their catalytic performance.

A series of iron-based Fischer–Tropsch catalysts, either pure or promoted with Ce or Mn, were subjected to different activation treatments with H2, CO, or H2/CO. The surface species formed after different treatments were characterized by temperature-programmed surface reaction with hydrogen (TPSR-H2) and temperature-programmed surface desorption with argon (TPD-Ar). After activation and temperature-programmed treatments, the samples were passivated and characterized by X-ray diffraction and Raman spectroscopy. After each activation treatment, the catalysts were tested in the Fischer–Tropsch synthesis, and selected postreaction samples were characterized by Mossbauer spectroscopy. After CO and syngas treatment, cementite (θ-Fe3C) and Hagg (χ-Fe2.5C) carbides were formed, respectively. Different surface carbonaceous species were stabilized over these carbides. Cementite species are less active in the Fischer–Tropsch synthesis; however, under the Fischer–Tropsch reaction environment, they can evolve into the Hagg carbide, over which the more active carbonaceous intermediate species are formed. Modification of the catalyst composition by Mn and Ce is effective only when the samples are activated under CO, accelerating the stabilization of active carbonaceous intermediates.

The microemulsion technology was used in order to improve the preparation of iron-based catalysts for the CO and CO2 hydrogenation reactions. This technique led to a sample with a higher surface area when compared with a similar solid prepared by conventional precipitation. As a consequence, a higher catalytic activity was obtained. The hydrogenation of carbon oxides was also performed over promoted iron-manganese catalysts. The preparation of these samples by the microemulsion methodology yielded to homogeneous mixed oxides. Manganese-containing catalysts presented a higher activity towards the formation of hydrocarbons, at the same conversion levels, than the iron counterparts. These catalysts were promoted with copper, sodium and potassium. Carbon dioxide conversion was favoured by alkaline addition, especially by potassium, due to the promotion of the water-gas shift reaction. Furthermore, alkaline promotion enhanced selectivity towards long-chain products either in CO2 and CO hydrogenation processes. Addition of copper caused a more facile reducibility of the solids, resulting in a significant increment in both carbon monoxide and carbon dioxide conversion without modifying products selectivity.

Chemical modification of Carbon Vulcan XC-72R for fuel cell applications has been undertaken. Treated carbons were used as carriers for the deposition of Pt nanoparticles and used as electrocatalysts. The influence of the carbon treatment, as well as that of the Pt nanoparticles generation and their deposition route has been studied. The behaviour of the electrocatalysts in the CO and hydrogen oxidation reaction (HOR) has been studied. It was observed that carbon pre-treatment lead to difference behaviour in the CO oxidation reaction compared with the performance over non treated supports. In this way, CO oxidation was controlled by the nature of the support rather than by the nature of the Pt particles alone.

The effect of the preparation method of PtRu electrocatalysts and the chemical treatment of support on the performance for methanol electrooxidation has been studied. Carbon supported PtRu catalysts were synthesized from aqueous solution of H 2 PtCl 6 and RuCl 3 precursors by two different methods: colloidal (using NaHSO 3 ) and impregnation. The carbon black Vulcan XC-72R was functionalised with H 2 O 2 and HNO 3 . A commercial PtRu/C catalyst purchased from Johnson and Matthey was used as reference. The obtained electrocatalysts were characterized by XPS, XRD, TEM, EGA-MS, TGA and TXRF. Chronoamperometry in methanol and CO ads stripping experiments were conducted to check their electrocatalytic activity. Electrocatalysts obtained by the colloidal method and supported on functionalised carbon black with HNO 3 and especially with H 2 O 2 , showed better performances (CO tolerance and superior methanol oxidation ability) than those obtained by the impregnation method and the commercial one.

A series of silica-supported iron samples has been prepared by the microemulsion technology. The samples were characterized by temperature programmed reduction (TPR), UV–vis spectroscopy, N2 adsorption isotherms, X-ray photoelectron spectra (XPS), SEM and transmission electron microscopy (TEM) microscopy and tested in the carbon monoxide and carbon dioxide hydrogenation reactions. Although all samples have similar composition and metallic loading, the preparation route was crucial for the actual nature of the samples, tuning also their catalytic performance. The main result of the preparation route was the extension of the degree of the interaction between the active phase and the support. As a consequence, samples where a metal–support interaction was promoted showed a lower reducibility and therefore a lower catalytic activity. The addition of Mn, Cu and K promoters improves the catalytic performance in carbon monoxide hydrogenation. The low activity of the samples in carbon dioxide hydrogenation is due to their low reverse water–gas shift activity.

Iron−manganese mixed oxides have been prepared by the microemulsion (MEM) technique, obtaining solids displaying homogeneously distributed Fe−Mn phases. For the sake of comparison similar samples prepared by different techniques have been studied. Magnetization measurements reveal that the extension of the Fe−Mn interaction was enhanced in the samples prepared by microemulsion and so was the sample homogeneity. The average size of the oxide particles prepared by microemulsion lies in the nanometer range, displaying also a narrow particle size distribution. A certain degree of manganese surface enrichment was observed for all samples and overall in those containing a larger amount of Mn, irrespective of the preparation method as revealed by X-ray photoelectron spectroscopy. Selected solids were used as catalyst precursors for the Fischer−Tropsch reaction. Mn promotion led to an enhancement of the olefin-to-paraffin ratio in the samples over which Fe−Mn interaction developed.

The titanium salycilate complex [Cp*Ti(sal)(salH)] 1 (salH 2 = salycilic acid) was synthesised by reacting Cp*TiMe 3 and salycilic acid. The molecular structure of 1 studied by X-ray shows it to be dinuclear with a carboxylate group acting as a bridge ligand. [Rh(μ-OH)COD] 2 reacts with 1 to yield the bimetallic complex 2 , or with the siloxanodiol (HOSiPh) 2 O to yield the bimetalic bis-siloxide Rh complex 3 . Carbon monoxide displaces COD in 2 and 3 to give the carbonylic complexes 4 and 5 respectively. Complex 4 can also be prepared from 2 and [Rh(acac)(CO) 2 ]. Compounds 2 , 3 , 4 and 5 can be envisaged as models of Rh complexes anchored on titania or silica. The catalytic performance of heterometallic complexes is studied in the CO hydrogenation reaction and compared to rhodium-based (Rh-based) catalysts prepared by impregnation from Rh(NO 3 ) 3 or [Rh(acac)(CO) 2 ] showing higher yields to oxygenated products.

PtRu nanoparticles deposited on a carbon black sub-strate are catalysts commonly employed for the electro-oxidation of methanol and carbon monoxide-containinghydrogen feeds [1,2]. However, improvement of effectiveelectrocatalysts is an essential goal in the development ofa practical DMFC. The use of carbon black as a supportfor noble metals is frequent in the electrodes of polymermembrane electrolyte fuel cells, but the impact of thechemical and physical properties of the carbon on elect-rocatalytic performance are not yet sufficiently under-stood. The presence of oxygen surface groupsinfluences the surface behaviour of carbons to a consid-erable extent [3,4]. As examples, the wettability andadsorptive behaviour of a carbon, as well as its catalyticand electrical properties, are influenced by the natureand extent of such surface groups. The varying role ofoxygenated functionalities on the formation of the dis-persed platinum has been established [5–8], but not withan additional metal such as ruthenium. In the presentinvestigation we report how the performance in metha-nol electrooxidation of PtRu nanoparticles depositedon a carbon black substrate, previously functionalizedwith oxygen surface groups, is improved.A commercial Vulcan XC-72R (Cabot Co.) carbonblack was used as the support material. This carbonwas functionalized by treatment with an aqueousH

Two series of Fe−Ce catalysts were prepared following two different methods: coprecipitation from Fe and Ce nitrate solutions and physical mixing of pure Fe and Ce precursors. Evidence of the presence of a chemical interaction between Fe and Ce was found in the calcined state of the coprecipitated catalysts. Such evidence was obtained with different techniques. The Fe−Ce interaction occurs through the formation of hematite-like and cubic ceria-like solid solutions. In the hematite-like solid solution, Ce cations are dissolved in the hematite structure, whereas in the cubic ceria-like solid solution Fe cations are dissolved in the ceria structure. Such interactions were absent in the samples prepared by the physical mixing. It is suggested that the Fe−Ce interaction present in the calcined state results in a strong Fe−Ce interaction in the final catalyst that defines their better catalytic properties. When tested in the Fischer−Tropsch synthesis of hydrocarbons from CO + H2 gas mixtures, the coprecipitati...

The temperature of calcination in air of a Rh/γ-Al 2 O 3 catalyst affects its structure in, at least, two different ways. First, upon increasing calcination temperature from 400 to 700 °C, the amount of non-reducible Rh 2 O 3 increases. But the most important effect is the sintering of metal particles, especially when the calcination temperature is around 700 °C or above. Catalytic activity in CO hydrogenation is strongly influenced as a consequence of this phenomenon. CO conversion decreases on larger rhodium particles, although turnover frequency (TOF) follows the opposite trend. In addition, oxygenates formation is strongly suppressed on the sintered catalysts.

The new tantalum dialkoxide complexes Cp*TaCl 2 (OCH 2 ) 2 py (1), trans-Cp*TaMe 2 (OCH 2 ) 2 -py (2), and cis-Cp*TaMe 2 (OCH 2 ) 2 py (3) (Cp* = η 5 -C 5 Me 5 ; (OCH 2 ) 2 py = 2,6-pyridinedimethoxide) have been synthesized. The molecular structures of complexes 1 and 2 have been studied by X-ray diffraction methods. The reaction of complex 3 with carbon monoxide renders Cp*Ta-(η 2 -Me 2 CO)(OCH 2 ) 2 py (4), while with isocyanides yields the respective azatantalacyclopropanes Cp*Ta(η 2 -Me 2 CNxylyl)(OCH 2 ) 2 py (6) (xylyl = 2,6-dimethylphenyl) and Cp*Ta(η 2 -Me 2 CN t Bu)(OCH 2 ) 2 py (7). The molecular structure of complex 4 has been established by X-ray diffraction. The coordinated ketone in 4 can be reduced to 2-propanol in the presence of water. On the other hand, compound 3 reacts with triflic acid (HOTf) to render the corresponding cationic derivative [Cp*TaMe(OCH 2 ) 2 py]OTf (8).

The early–late heterometallic complexes [TiCp∗((OCH2)2Py)(μ-O)M(COD)] (M = Rh, Ir) behave as four-electron donor ligands yielding the polynuclear cationic complexes [TiCp∗(OCH2)2 Py(μ-O){M(COD)}2]OTf (M = Rh (1), Ir (2)). The molecular structure of complex 1 has been established through an X-ray diffraction study.

A support for enzyme immobilization was prepared by functionalization of mesoporous silica with octyltriethoxysilane. The features of the surface enables the adsorption of lipase from Candida antarctica B via strong hydrophobic interactions, enhancing the stability of the adsorbed enzyme molecules. Derivatives with a high enzyme loading (200 mg protein/g of silica) can be obtained due to the high porosity and surface properties of the support while the immobilization occurs in a monolayer fashion. The lack of inactive enzyme aggregates, together with the high enzyme loading, are responsible for the high catalytic activity achieved by these species. Derivatives were prepared with different lipase loading, and the activities were tested and compared to the commercial derivative Novozym 435. The stability of the catalyst and hence its industrial applicability were tested by performing subsequent reaction cycles of acylation of ethanolamine with lauric acid in acetonitrile. Conversion was quantitative even after 15 reaction cycles.

The effect of manganese promoter loading on the catalytic properties of Rh/Al2O3 catalysts (Mn/Rh=0, 0.5, 1 and 2, atomic ratio) for the synthesis of oxygenated compounds from synthesis gas was investigated. Catalysts were characterized by means of TPR, XPS, H2 chemisorption, FT-IR, and TPSR of chemisorbed CO. It is suggested that manganese oxide promotes CO conversion as a result of the change in the relative surface coverage of H* and C* (θH/θC). The manganese oxide promoter also affected the selectivity to oxygenated compounds, mainly to ethanol. The manganese promoter behaved as an electron-withdrawing, partially oxidizing the rhodium atoms at the Rh–MnO interface and thus creating new sites for CO insertion. The amount of promoter seemed to be an important parameter to achieve the highest yield of the desired reaction products. For oxygenates formation, the optimum Mn/Rh atomic ratio was found to be around 1.

In the present work, organometallic complexes were used as metal precursors for the synthesis of sulphur-resistant noble metal catalysts. The catalysts were tested in the hydrogenation reaction of diesel model-type molecules. Dibenzothiophene (DBT) was used as the source of sulphur. The organometallic-based catalysts activity was compared with the activity displayed by a commercial Pt/Al 2 O 3 hydrogenation catalyst. Comparable activity results were obtained when the reaction was carried in the presence of sulphur containing molecules. However, the organometallic-based catalysts were only active once the ligands had been removed from the metal coordination sphere, thus allowing the reactant molecules to adsorb on the metallic surface centres. Accordingly, the major advantage of this methodology may lie in improved metallic dispersion, which will be reflected in catalysts with greater sulphur resistance, rather than in the electronic or steric effects ascribed to organometallic precursors.

Modification of the multistep synthesis of the previously described bis[5-(diphenylphosphanyl)pyrazol-1-yl)]methane (bppzm, 1) produces the novel diphosphane (diphenylphosphanyl)-[5-(diphenylphosphanyl)pyrazol-1-yl](pyrazol-1-yl)methane (p4m, 2). Treatment of this ligand with [MCl2(PhCN)2] (M = Pd, Pt) or [M(COD)(THF)2]BF4 (M = Rh, Ir) produces [MCl2(p4m)] (M = Pd 3, Pt 4) or [M(COD)(p4m)]BF4 (M = Rh 5, Ir 6) complexes, which chelate in a P,P-bidentate fashion. Sulfidation of bppzm and p4m produces the disulfidophosphanes bppzmS2 (7) and p4mS2 (8). Treatment of 7 and 8 with [PdCl2(PhCN)2] produces [PdCl2(bppzmS2)] (9) and [PdCl2(pmS2)] (10), respectively, in which ligands 7 and 8 act in an N,N-bidentate chelate fashion. In contrast, ligand 8 reacts with [Rh(COD)(THF)2]BF4 to produce [Rh(COD)(p4mS2)]BF4, where ligand 7 acts in a dynamic S,S-chelate fashion. The activity of some of these complexes in the catalytic hydrogenation of olefins is reported and the single-crystal X-ray structures of 4, 8, and 9 have been obtained. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Silica-supported rhodium catalysts prepared from nitrate and chloride precursors were tested in the CO hydrogenation reaction. Similar reaction rate and selectivities to the different product families were found for both catalysts, however the ex-chloride catalyst showed a lower 1-olefin/n-paraffin ratio. Characterisation by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), H2 chemisorption and Fourier transform infrared spectroscopy (FTIR) of CO chemisorbed did not evidence disparate features between ex-nitrate and ex-chloride samples. However, a much higher H2 desorption was found in the ex-chloride catalyst according to the hydrogen temperature-programmed desorption (TPD) studies. Residual chloride species seems to be involved in the H2 adsorption on silica enhancing the spillover of hydrogen from metal particles to the silica support. It is suggested that spilt-H atoms can create active sites on the silica surface where olefins can be hydrogenated to the corresponding paraffins.

New monocyclopentadienyl species of TaV, [Cp*TaL3(XR)] (L = Cl, Me, X = O, S) bearing 4,6-dimethyl-2-pyrimidinethiolate (SR = SC6H7N2) or 3-cyano-4,6-dimethyloxypyridine (OR = OC8H7N2) ligands were prepared, namely [Cp*TaCl3(SC6H7N2)] (1), [Cp*TaCl3(OC8H7N2)] (2), [Cp*TaMe3(SC6H7N2)] (3). In addition, a bis(oxypyridine)titanium(IV) complex [Cp*TiMe2(OC8H7N2)2] was isolated. The X-ray structure analysis of 1 revealed that the thiolate group is bonded to the metal center through the sulfur atom and one of the nitrogen atoms in an η2-fashion. The reactivity of complex 3 with isocyanides (CNR), R = tBu, Xyl (Xyl = 2,6-dimethylphenyl) was also studied showing differences depending on the nature of R group. The reaction with 2,6-dimethylphenyl isocyanide gives the azatantalacyclobutane complex [Cp*TaMe{XylN=CC(Me2)NXyl}(SC6H7N2)] (5) as the final product, whereas in the reaction with tert-butyl isocyanide the η2-imine-containing complex [Cp*Ta{tBuNC(Me2)}(SC6H7N2)] (6) is proposed to be formed. The dynamic behavior of [Cp*TaMe3(SC6H7N2)] (3) was also studied by variable-temperature 1H NMR spectroscopy. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

The rhodium thiopyrimidine complex [Rh(SPymMe 2 )(CO) 2 ] was tethered to chemically modified SiO 2 substrates and tested as a catalyst in the hydroformylation reaction of 1-heptene. Catalytic performance was monitored under different reaction conditions for several cycles, and compared with the catalytic behaviour of the Rh thiolate complex in a homogeneous medium. Anchoring of the rhodium complex to the modified SiO 2 surface was performed by displacement of a CO ligand of the rhodium complex by a PR 3 group, following a reaction pathway previously described for gem–dicarbonilic complexes. The XPS data revealed that the sulphur atom is released from the external surface of the solid catalyst during the hydroformylation reaction. However, the thiolate complex is still present in the inner pore network of the solid after the hydroformylation reaction.

This paper presents a study of the effects of different treatments on the polymerization activity of mod-ified clays as cocatalysts. To achieve this goal, an intercalating cation was introduced into two smectitesand these clays were then modified with trimethyl aluminium. The results for ethylene polymeriza-tion, when a zirconocene complex was used as catalyst, and the structure analysis, allow us to obtaininteresting deductions about the generation mode of the active species. All active materials employedas support activators presented aluminium in a pentahedral environment together with acidic hydrogenatoms. These two features were detected only after TMA treatment and they seem to be crucial elementsin active cocatalyst generation. Moreover, a material without structural aluminium displayed the bestactivity pointing to the new aluminium species generated in the solid matrix as the determining factorfor the activity. We proposed a synergic effect between Lewis acid aluminium centres and acidic Brönstedprotons that generate the SiOHAl groups that activate the zirconium compound.

Rhodium thiolate complexes intercalated in crystalline γ-zirconium phosphate or tethered to SiO2-modified γ-zirconium phosphate have been synthesised. It was observed that the addition of a solution of organic silicates to a colloidal suspension of γ-zirconium phosphate yielded amorphous substrates, which displayed very high specific areas (160–650 m2 g−1). Incorporation of a mercaptocarbonyl rhodium complex resulted in a highly selective and active catalyst precursor for the hydroformylation of 1-heptene in the liquid phase. Elemental analysis and photoelectron spectroscopy of the fresh and used samples revealed that some metal leaching occurs during the reaction, this being mainly confined to the outer layers of the solid particles. This observation, together with the high selectivity towards linear aldehydes, makes SiO2-modified γ-zirconium phosphate a good support candidate for immobilised Rh catalysts. Spectroscopic data obtained from the crystalline precursor and also from the amorphous catalyst showed that the interaction between the rhodium complex and the acid support was achieved ia hydrogen bonds, forming NH groups.

Rhodium supported on titania-silica is modeled by 1, which was obtained from [{Cp*TiMe(μ-O2 SiPh2 )}2 ] (2) and [{Rh(OH)(cod)}2 ]. Complex 2 and its triply bridged derivative [Cp*Ti(μ-O2 SiPh2 )3 TiCp*] (3) can be envisaged as molecular models of titania-silica systems. Compounds 1-3 could potentially provide insights into the nature of the catalytically active sites in these systems; cod=1,5-cycloctadiene, Cp*=η5 -C5 Me5 .

Cp*TaCl4 reacts with X(CH2CH2SH)2 in the presence of NEt3 to yield the corresponding thiolate complexes Cp*TaCl2(SCH2CH2)2X (X = O (1), S (2)). The crystal structure of complex 2 has been determine...

Halo-alkoxide zirconocene complexes (η5-C5Me5)2ZrCl(OCH2CH2SPh) (1) and (η5-C5Me5)2ZrCl(OC6H4SH) (2) have been prepared by reaction of the corresponding zirconocene dichloride with HOCH2CH2SPh or HOC6H4SH, respectively, in the presence of NEt3. The molecular structure of 1 has been determined by X-ray diffraction studies. Alkyl- and aryl-containing species (η5-C5Me5)2ZrMe(OCH2CH2SPh) (3) and (η5-C5Me5)2ZrPh(OCH2CH2SPh) (4) were synthesised by reaction of the corresponding dialkyl or diaryl species with HOCH2CH2SPh, or by reaction of complex 1 with LiMe or LiPh, respectively. Finally, the dialkoxide complexes L2M(OCH2CH2SR)2 [L=η5-C5H5, M=Ti, R=Ph (5); L=η5-C5Me5, M=Ti, R=Ph (6); L=η5-C5Me5, M=Ti, R=Me (7)] were prepared by reaction of the appropriate dichloride and alcohol in the presence of NEt3, and (η5-C5H5)2Zr(OCH2CH2SMe)2 (8) was synthesised by reacting (η5-C5H5)2ZrMe2 with two equivalents of HOCH2CH2SMe.

The methyltitanium derivative TiCp*Me3 (Cp* = η5-C5Me5) reacted with tris(2-pyridyl)methyl alcohol, HOCPy3, to yield the alkoxide complex TiCp*Me2(OCPy3) 1. The reaction of TiCp*Me3 with di-2-pyridyl ketone, Py2CO, yielded, through an insertion process, the corresponding alkoxide derivative TiCp*Me2(OCMePy2) 2. In order to establish the co-ordination mode of the alkoxide ligand, X-ray diffraction studies were carried out on complex 2. Insertion of di-2-pyridyl ketone into a Ta–Me bond of TaCp*Me4 gave the corresponding alkoxide compound TaCp*Me3(OCMePy2) (3). Metathesis reaction of titanium and zirconium complexes MCp*Cl3 with the lithium alkoxide LiOCRPy2 led to the corresponding derivatives MCp*Cl2(OCRPy2) [M = Ti, R = Me (4) or Py (5); M = Zr, R = Me (6) or Py (7)]. In an analogous way, tantalum derivatives TaCp*Cl3(OCRPy2) [R = Me (8) or Py (9)] can also be synthesized by reaction of TaCp*Cl4 with the appropriate lithium alkoxide LiOCRPy2. The crystal structure of complex 9 has been determined by X-ray diffraction.

The reaction of Cp*TiMe3 with 3 equiv of [Ir(μ-OH)(COD)]2 affords the new heterometallic organometallic oxide Cp*Ti(μ3-O)3[Ir(COD)]3 (3). Reaction of Cp*TaMe4 with 4 equiv of [M(μ-OH)(COD)]2 (M = Rh, Ir) yields complexes Cp*Ta(μ3-O)4[M(COD)]4 [M = Rh (5), Ir (6)]. The structure of compound 5 has been determined by X-ray diffraction. Complexes 5 and 6 react with the alcohol 3-CN-4,6-Me2-2-OH−C5HN to yield the corresponding rhodium (7) or iridium (8) alkoxide complexes. The structure of complex 8 has been determined by X-ray diffraction. Reaction of [Rh(μ-OH)(COD)]2 with thiolacetic acid gives rise to a thioacetate complex [Rh(μ-SCOCH3)(COD)]2 (9).

Iridium–fluorobenzenetiolate complexes of general formula [Ir(SRF)(CO)(PPh3)2], (RF=C6F5 1a, C6HF4-4 1b, C6H4F-4 1c, and C6H4CH3-2 1d), were prepared by methatetical reactions with Tl(SRF) or HSRF. The unexpected trimetallic compound [Ir3(μ-SC6F5)3(μ-CO)(CO)4(PPh3)2] 2 was also isolated when RF=C6F5. Oxidative addition of fluorothiols to the corresponding Ir(I) precursors, afforded the compounds [Ir(H)(Cl)(SRF)(CO)(PPh3)2] (RF=C6F5 3a, C6HF4-4 3b and C6H4F-4 3c) and [Ir(H)(SRF)2(CO)(PPh3)2])] (RF=C6F5 4a, C6HF4-4 4b and C6H4F-4 4c). Irreversible oxygen uptake by compounds 1 gives rise to the oxo-derivatives [Ir(SRF)(O2)(CO)(PPh3)] (RF=C6F5 5a, C6HF4-4 5b, C6H4F-4 5c and C6H4CH3-2 5c). The crystal and molecular structures of [Ir(SC6F5)(CO)(PPh3)2] 1a, [Ir3(μ-SC6F5)3(μ-CO)(CO)4(PPh3)2] 2 and [Ir(SC6F5)(η2-O2)(CO)(PPh3)2] 5a were determined by X-ray diffraction crystallography. Compound 2 contains an asymmetrical Ir3S3 ring with one iridium–iridium bond (2.665(1)A) doubly bridged by CO and (C6F5S)−.

The reaction of Cp2ZrCl2 (Cp = η5-C5H5) with 2 equiv of the lithium amide derivative LiNHC6H4-o-SMe affords the new zirconium complex Cp2Zr(NHC6H4-o-SMe)2 (2). The structure of 2 has been determined by X-ray diffraction. When the reaction is carried out in an 1:1 ratio, the complex Cp2ZrCl(NHC6H4-o-SMe) (3) is generated as the major product. Reaction of “Cp*2Zr” (Cp* = η5-C5Me5) with 2-(methylmercapto)aniline yields a hydride−amide complex Cp*2ZrH(NHC6H4) (4). Reaction of complex 2 with [RhCl(COD)]2 generates complex 3 and the new rhodium amide complex Rh(NHC6H4-o-SMe)(COD), which has been also directly synthesized by reacting [RhCl(COD)]2 with LiNHC6H4-o-SMe. Thermolysis of complex 6, at 100 °C, produces to a new rhodium thiolate complex [Rh(μ-SC6H4-o-NHMe)(COD)]2 (5). Its structure has been determined by X-ray diffraction methods. Reaction of [IrCl(COD)]2 with LiNHC6H4-o-SMe gives the iridium(III) complex Ir(Me)(SC6H4NH)(COD) (7) by oxidative addition of the S−Me bond.

The perfluorothiolate dinuclear compounds [Rh( μ -SC 6 F 5 )(COD)[ 2 1 and [Rh( μ -SC 6 F 5 )(CO) 2 [ 2 2 react with PPh 3 to give monomeric and dimeric complexes, the particular product depending upon the PR 3 /Rh ratio and reaction conditions. Reaction of 2 with 2 moles of PPh 3 renders cis - 7 and trans -[Rh( μ -SC 6 F 5 )((CO)(PPh 3 )[ 2 8 , while with 4 moles of PPh 3 trans [Rh(SC 6 F 5 )(CO)(PPh 3 ) 2 [ 10a is obtained. This latter product can otherwise be prepared by Cl metathesis from trans -[RhCl(CO(PPh 3 ) 2 [ in toluene. This same reaction in dichloromethane however yields the cis isomer 10b . When a larger excess of PPh 3 is used, a mixture of compounds 11a and 11b is formed. An X-ray crystal structure study shows trans [Rh(SC 6 F 5 )(CO)(PPh 3 ) 2 [ to exit as two polymorphs. 11a crystallises in the space group P2 1 /n of the monoclinic system with a = 12.489(1), b = 15.430(5), c = 19.719(1) A, α = γ = 90, β = 92.84(1)°, and 11b is triclinic, space group P1¯ with a = 9.764(2), b = 12.197(6), c = 17.880 A, α = 100.18(5), β = 101.92(2), γ = 113.61(2)°. Both PPh 3 ligands are mutually trans and the difference in v (CO) stretching frequencies 1989 and 1939 cm −1 , can be explained in terms of o-phenyl H…CO interactions in the latter. The [Rh( μ -SC 6 F 5 )(COD)[ 2 1 and [Rh( μ -SC 6 F 5 )(CO) 2 [ 2 2 /nPPh 3 systems have been studied as catalyst precursors for the hydroformylation of 1-heptene in toluene at 30 bar and 343 K. Selectivity towards the linear aldehyde is enhanced when dimeric complexes are used.

The thiolate−alkylzirconocene complex Cp2ZrMe(SR) (2) (Cp = η5-C5H5; SR = 4,6-dimethylpyrimidine-2-thiolate) can be prepared by reacting the corresponding dialkylmetallocene complex Cp2ZrMe2 (1) with 1 equiv of 4,6-dimethyl-2-mercaptopyrimidine. X-ray structure analysis of complex 2 revealed that the thiolate group is bonded in an η2 fashion through the sulfur and one of the nitrogen atoms. Complex 2 reacts with 2,6-dimethylphenyl isocyanide (CNXylyl) to yield the corresponding iminoacyl derivative, Cp2Zr(η2-MeCNXylyl)(SR) (4). The molecular structure of 4 shows that the thiolate group is η1-bonded while the iminoacyl group behaves as a bidentate ligand. Reaction of compound 2 with different acidic reagents gives formation of methane and different zirconium complexes. Reaction with HSR renders Cp2Zr(SR)2 (3) and with (NHEt3)(BPh4) the cationic complex [Cp2Zr(SR)][BPh4] (5). An hydride thiolate complex, Cp*2ZrH(SR) (Cp* = η5-C5Me5) (6) can also be prepared by reaction of “Cp*2Zr” with HSR by an oxidative a...