ß-(Z)-Selective alkyne hydrosilylation by a N,O-functionalized NHC-based rhodium(I) catalyst.

Neutral and cationic cyclooctadiene rhodium(I) complexes with a lutidine-derived polydentate ligand having NHC and methoxy side-donor functions, [RhBr(cod)(κC-tBuImCH2PyCH2OMe)] and [Rh(cod)(κ2C,N-tBuImCH2PyCH2OMe)]PF6, have been prepared. Carbonylation of the cationic compound yields the dicarbonyl complex [Rh(CO)2(κ2C,N-tBuImCH2PyCH2OMe)]PF6 whereas carbonylation of the neutral compound affords a mixture of di- and monocarbonyl neutral complexes [RhBr(CO)2(κC-tBuImCH2PyCH2OMe)] and [RhBr(CO)(κ2C,N-tBuImCH2PyCH2OMe)]. These complexes efficiently catalyze the hydrosilylation of 1-hexyne with HSiMe2Ph with a marked selectivity towards the ß-(Z)-vinylsilane product. Catalyst [RhBr(CO)(κ2C,N-tBuImCH2PyCH2OMe)] showed a superior catalytic performance, in terms of both activity and selectivity, and has been applied to the hydrosilylation of a range of 1-alkynes and phenylacetylene derivatives with diverse hydrosilanes, including HSiMe2Ph, HSiMePh2, HSiPh3 and HSiEt3, showing excellent ß-(Z) selectivity for the hydrosilylation of linear aliphatic 1-alkynes. Hydrosilylation of internal alkynes, such as diphenylacetylene and 1-phenyl-1-propyne, selectively affords the syn-addition vinylsilane products. The ß-(Z) selectivity of these catalysts contrasts with that of related rhodium(I) catalysts based on 2-picolyl-functionalised NHC ligands, which were reported to be ß-(E) selective. An energy barrier ΔG‡ of 19.8 ± 2.0 kcal mol-1 (298 K) has been determined from kinetic studies on the hydrosilylation of 1-hexyne with HSiMe2Ph. DFT studies suggest that the methoxy-methyl group is unlikely to be involved in the activation of hydrosilane, and then hydrosilane activation is likely to proceed via a classical Si-H oxidative addition.

Selective Oxidation of Glycerol via Acceptorless Dehydrogenation Driven by Ir(I)-NHC Catalysts.

Iridium(I) compounds featuring bridge-functionalized bis-NHC ligands (NHC = N-heterocyclic carbene), [Ir(cod)(bis-NHC)] and [Ir(CO)2(bis-NHC)], have been prepared from the appropriate carboxylate- or hydroxy-functionalized bis-imidazolium salts. The related complexes [Ir(cod)(NHC)2]+ and [IrCl(cod)(NHC)(cod)] have been synthesized from a 3-hydroxypropyl functionalized imidazolium salt. These complexes have been shown to be robust catalysts in the oxidative dehydrogenation of glycerol to lactate (LA) with dihydrogen release. High activity and selectivity to LA were achieved in an open system under low catalyst loadings using KOH as a base. The hydroxy-functionalized bis-NHC catalysts are much more active than both the carboxylate-functionalized ones and the unbridged bis-NHC iridium(I) catalyst with hydroxyalkyl-functionalized NHC ligands. In general, carbonyl complexes are more active than the related 1,5-cyclooctadiene ones. The catalyst [Ir(CO)2{(MeImCH2)2CHOH}]Br exhibits the highest productivity affording TONs to LA up to 15,000 at very low catalyst loadings.

Copper-Catalyzed Azide-Alkyne Cycloaddition (CuAAC) by Functionalized NHC-Based Polynuclear Catalysts: Scope and Mechanistic Insights.

Copper(I) [Cu2(µ-Br)2(tBuImCH2pyCH2L)] n (L = OMe, NEt2, NHtBu) compounds supported by flexible functionalized NHC-based polydentate ligands have been prepared in a one-pot procedure by reacting the corresponding imidazolium salt with an excess of copper powder and Ag2O. An X-ray diffraction analysis has revealed that [Cu2(µ-Br)2(tBuImCH2pyCH2NEt2)] n is a linear coordination polymer formed by bimetallic [Cu(µ-Br)]2 units linked by the lutidine-based NHC-py-NEt2 ligand, which acts as a heteroditopic ligand with a 1κC-2κ2 N,N' coordination mode. We propose that the polymeric compounds break down in the solution into more compact tetranuclear [Cu2(µ-Br)2(tBuImCH2pyCH2L)]2 compounds with a coordination mode identical to the functionalized NHC ligands. These compounds have been found to exhibit high catalytic activity in the Cu-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. In particular, [Cu2(µ-Br)2(tBuImCH2pyCH2NEt2)]2 efficiently catalyzes the click reaction of a range of azides and alkynes, under an inert atmosphere at room temperature in neat conditions at a very low catalyst loading, to quantitatively afford the corresponding 1,4-disubstituted 1,2,3-triazole derivatives in a few minutes. The cycloaddition reaction of benzyl azide to phenylacetylene can be performed at 25-50 ppm catalyst loading by increasing the reaction time and/or temperature. Reactivity studies have shown that the activation of the polynuclear catalyst precursor involves the alkyne deprotonation by the NHC moiety of the polydentate ligand to afford a copper(I)-alkynyl species bearing a functionalized imidazolium ligand. DFT calculations support the participation of the dinuclear species [(CuBr)2(µ-tBuImCH2pyCH2NEt2)], resulting from the fragmentation of the tetranuclear compound, as the catalytically active species. The proposed reaction pathway proceeds through zwitterionic dinuclear intermediates and entails the active participation of both copper atoms, as well as the NHC moiety as an internal base, which activates the reacting alkyne via deprotonation.

Catalytic applications of zwitterionic transition metal compounds.

This frontiers article highlights recent developments on the application of transition metal-based zwitterionic complexes in catalysis. Recent applications of selected zwitterionic catalysts in polymerization reactions, including the carbonylative polymerization of cyclic ethers, carbon-carbon coupling reactions, the asymmetric hydrogenation of unfunctionalized olefins, and the hydrofunctionalization of alkenes are reviewed. In addition, advances in the field of hydrogenation/dehydrogenation reactions related to energy applications, including the hydrogenation of CO2 and the dehydrogenation of formic acid and N-heterocycles, the functionalization of CO2 with amines and hydrosilanes, and the valorization of polyfunctional bio-based feedstocks, such as the dehygrogenation of glycerol to lactic acid or the reduction of levulinic acid into γ-valerolactone, are also described.

Zwitterionic Rhodium and Iridium Complexes Based on a Carboxylate Bridge-Functionalized Bis-N-heterocyclic Carbene Ligand: Synthesis, Structure, Dynamic Behavior, and Reactivity.

A series of water-soluble zwitterionic complexes featuring a carboxylate bridge-functionalized bis-N-heterocyclic carbene ligand of formula [Cp*MIIICl{(MeIm)2CHCOO}] and [MI(diene){(MeIm)2CHCOO}] (Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl; M = Rh, Ir; MeIm = 3-methylimidazol-2-yliden-1-yl; diene = 1,5-cyclooctadiene (cod), norbornadiene (nbd)) were prepared from the salt [(MeImH)2CHCOO]Br and suitable metal precursor. The solid-state structure of both types of complexes shows a boat-shaped six-membered metallacycle derived of the κ2C,C' coordination mode of the bis-NHC ligand. The uncoordinated carboxylate fragment is found at the bowsprit position in the Cp*MIII complexes, whereas in the MI(diene) complexes it is at the flagpole position of the metallacycle. The complexes [RhI(diene){(MeIm)2CHCOO}] (diene = cod, nbd) exist as two conformational isomers in dichloromethane, bowsprit and flagpole, that interconvert through the boat-to-boat inversion of the metallacycle. An inversion barrier of ∼17 kcal·mol-1 was determined by two-dimensional exchange spectroscopy NMR measurements for [RhI(cod){(MeIm)2CHCOO}]. Reaction of zwitterionic Cp*MIII complexes with methyl triflate or tetrafluoroboric acid affords the cationic complexes [Cp*MIIICl{(MeIm)2CHCOOMe}]+ or [Cp*MIIICl{(MeIm)2CHCOOH}]+ (M = Rh, Ir) featuring carboxy and methoxycarbonyl functionalized methylene-bridged bis-NHC ligands, respectively. Similarly, complexes [MI(diene){(MeIm)2CHCOOMe}]+ (M = Rh, Ir) were prepared by alkylation of the corresponding zwitterionic MI(diene) complexes with methyl triflate. In contrast, reaction of [IrI(cod){(MeIm)2CHCOO}] with HBF4·Et2O (Et = ethyl), CH3OTf, CH3I, or I2 gives cationic iridium(III) octahedral complexes [IrIIIX(cod){(MeIm)2CHCOO}]+ (X = H, Me, or I) featuring a tripodal coordination mode of the carboxylate bridge-functionalized bis-NHC ligand. The switch from κ2C,C' to κ3C,C',O coordination of the bis-NHC ligand accompanying the oxidative addition prevents the coordination of the anions eventually formed in the process that remain as counterions.

Oxidation and ß-Alkylation of Alcohols Catalysed by Iridium(I) Complexes with Functionalised N-Heterocyclic Carbene Ligands.

The borrowing hydrogen methodology allows for the use of alcohols as alkylating agents for CC bond forming processes offering significant environmental benefits over traditional approaches. Iridium(I)-cyclooctadiene complexes having a NHC ligand with a O- or N-functionalised wingtip efficiently catalysed the oxidation and ß-alkylation of secondary alcohols with primary alcohols in the presence of a base. The cationic complex [Ir(NCCH3 )(cod)(MeIm(2- methoxybenzyl))][BF4 ] (cod=1,5-cyclooctadiene, MeIm=1-methylimidazolyl) having a rigid O-functionalised wingtip, shows the best catalyst performance in the dehydrogenation of benzyl alcohol in acetone, with an initial turnover frequency (TOF0 ) of 1283 h(-1) , and also in the ß-alkylation of 2-propanol with butan-1-ol, which gives a conversion of 94 % in 10 h with a selectivity of 99 % for heptan-2-ol. We have investigated the full reaction mechanism including the dehydrogenation, the cross-aldol condensation and the hydrogenation step by DFT calculations. Interestingly, these studies revealed the participation of the iridium catalyst in the key step leading to the formation of the new CC bond that involves the reaction of an O-bound enolate generated in the basic medium with the electrophilic aldehyde.

Synthesis and dynamic behaviour of zwitterionic [M(η(6)-C6H5-BPh3)(coe)2] (M = Rh, Ir) cyclooctene complexes.

The synthesis and structural characterization of zwitterionic [(η(6)-C6H5-BPh3)M(coe)2] (M = Rh, Ir) cyclooctene complexes is described. Both complexes exhibit an unusual exo-endo conformation of both cyclooctene ligands in the solid state. However, an equilibrium between the endo-endo and exo-endo rotational isomers arising from the hindered rotation about the metal-cyclooctene bond is observed in solution. Rotational barriers of around 65 kJ mol(-1) (Rh) and 84 kJ mol(-1) (Ir) have been determined by 2D EXSY NMR spectroscopy. The rotation process has also been studied by DFT calculations that showed that the dynamic behaviour is a consequence of the oscillation of the cyclooctene ligands about the metal-olefin bond instead of completing a full rotation.

Bis(hydrosulfido)-bridged dinuclear rhodium(I) complexes as a platform for the synthesis of trinuclear sulfido aggregates with the core [MRh2(µ3-S2)] (M = Rh, Ir, Pd, Pt, Ru).

The reaction of [Rh(µ-SH)(CO)(PPh(3))](2) or [Rh(µ-SH){P(OPh)(3)}(2)](2) with [Cp*MCl(2)](2) (M = Rh, Ir) in the presence of NEt(3) afforded the Rh(3) and IrRh(2) sulfido-bridged compounds [Cp*M(µ(3)-S)(2)Rh(2)(CO)(2)(PPh(3))(2)] (M = Rh, 1; Ir, 2) and [Cp*Rh(µ(3)-S)(2)Rh(2){P(OPh)(3)}(4)] (3). The reaction with [MCl(2)(cod)] (M = Pd, Pt), cis-[PtCl(2)(PPh(3))(2)] or [(η(6)-C(6)H(6))RuCl(2)](2) under the same experimental conditions gave [(cod)M(µ(3)-S)(2)Rh(2){P(OPh)(3)}(4)] (M = Pd, 6; Pt, 7), [(cod)M(µ(3)-S)(2)Rh(2)(CO)(2)(PPh(3))(2)] (M = Pd, 8; Pt, 9), [(PPh(3))(2)Pt(µ(3)-S)(2)Rh(2)(CO)(2)(PPh(3))(2)] (10) and [(η(6)-C(6)H(6))Ru(µ(3)-S)(2)Rh(2)(CO)(2)(PPh(3))(2)] (12), with PdRh(2), PtRh(2) and RuRh(2) trimetallic cores. The aggregates derived from [Rh(µ-SH)(CO)(PPh(3))](2) were isolated as a mixture of trans and cis isomers in which the trans isomer predominates. The reaction of [Rh(µ-SH){P(OPh)(3)}(2)](2) with 2 equiv. of n-BuLi at 253 K followed by addition of [Cp*IrCl(2)](2) gave [Cp*Ir(µ(3)-S)(2)Rh(2){P(OPh)(3)}(4)] (4) and [Cp*(2)ClIr(2)(µ(3)-S)(2)Rh{P(OPh)(3)}(2)] (5) in a 3 : 2 ratio. The RuRh(2) compound [(η(6)-C(6)H(6))Ru(µ(3)-S)(2)Rh(2){P(OPh)(3)}(4)] (11) was prepared similarly from [Rh(µ-SH){P(OPh)(3)}(2)](2) and [(η(6)-C(6)H(6))RuCl(2)](2) using n-BuLi as a deprotonating agent. The molecular structures of compounds 3, 6, 7, 9 and 11 have been determined by X-ray analysis. The trinuclear complexes exhibit an asymmetric triangular metal core with two triply bridging sulfido ligands resulting in a distorted trigonal-bipyramidal M(3)(µ(3)-S)(2) heterometallic metal-sulfur core.

Resultados negativos asociados a la medicación que son causa de visita al servicio de urgencias de un centro de atención primaria / Pharmacotherapy negative outcomes resulting in Primary Care Emergency visits

Objetivo: Analizar la prevalencia de los resultados negativos asociados a la medicación (RNM) que son causa de consulta en un servicio de urgencias de atención primaria (SUAP) en un entorno rural. Determinar la evitabilidad y la gravedad de los mismos. Diseño: Estudio observacional descriptivo transversal. Emplazamiento: SUAP de Mula. Murcia. Participantes: Un total de 330 pacientes, en un periodo de 33 semanas. Mediciones principales: Número y tipo de RNM: el farmacéutico, a través de los datos obtenidos de un cuestionario validado y la historia clínica, evaluó si existía relación entre los medicamentos que toma el paciente y el motivo de acudir a urgencias. En caso de sospecha de RNM se reevaluaba con el médico y se confirmaban o no los RNM identificados. Resultados: De los 330 pacientes fueron evaluables 317. La media de edad de los pacientes era de 39,63 años y el 51,42% eran mujeres. La media de medicamentos que utilizaban fue de 1,38. Se detectaron un 26,50% (IC 95% 21,94-31,62) de pacientes con RNM como causa de visita a urgencias. El 53,57% de los RNM detectados fue de la categoría de efectividad y el 40,48% de necesidad. El 77,41% (IC-95% 67,35-85,01) de las visitas causadas por RNM fueron evitables. En cuanto a la gravedad, el 92,986% de los RNM eran leves. Conclusiones: Una de cada 4 visitas al SUAP de Mula está causada por un RNM y, de ellas, el 77,41% son evitables(AU()

Objective: Our aim was to estimate the prevalence of Pharmacotherapy negative outcomes in Primary Care Emergency visits in a rural environment, and to determine their preventability and severity. Design: Descriptive study with an analytical component. Site: Primary Care Emergency Service (SUAP), Mula Murcia. Patients: The study consisted of 330 patients over a 33 week period. Method: Number and type of Pharmacotherapy negative outcomes: Pharmacist through the data, a validated questionnaire and medical history, assessing whether there was a relationship between the medications and the patient, and the reason for going to the Primary Care Emergency. In case of suspicion of Pharmacotherapy negative outcomes the patient is reassessed by the doctor, and the Pharmacotherapy negative outcomes confirmed or not identified. Results: Of the 330 patients, 317 were evaluable. The mean age of patients was 39.63 years and 51.42% were women. The mean number of drugs used was 1.38, and 26.50% (95% CI, 21.94% -31.62%) patients were detected with Pharmacotherapy negative outcomes as a cause of visiting the Primary Care Emergency. 53.57% of the detected Pharmacotherapy negative outcomes detected as regards efficacy was 53.75%, 40.48% as regards need. More than three-quarters (77.41%; 95% CI, 67.35% -85.01%) of emergency visits caused by Pharmacotherapy negative outcomes were avoidable. In terms of severity, 92.86% of the Pharmacotherapy negative outcomes were mild. Conclusions: One in four Mula SUAP visits are due to a Pharmacotherapy negative outcomes, and 77.41% of them are preventable(AU)

[Pharmacotherapy negative outcomes resulting in Primary Care Emergency visits]. / Resultados negativos asociados a la medicación que son causa de visita al servicio de urgencias de un centro de atención primaria.

OBJECTIVE: Our aim was to estimate the prevalence of Pharmacotherapy negative outcomes in Primary Care Emergency visits in a rural environment, and to determine their preventability and severity. DESIGN: Descriptive study with an analytical component. SITE: Primary Care Emergency Service (SUAP), Mula. Murcia. PATIENTS: The study consisted of 330 patients over a 33 week period. METHOD: Number and type of Pharmacotherapy negative outcomes: Pharmacist through the data, a validated questionnaire and medical history, assessing whether there was a relationship between the medications and the patient, and the reason for going to the Primary Care Emergency. In case of suspicion of Pharmacotherapy negative outcomes the patient is reassessed by the doctor, and the Pharmacotherapy negative outcomes confirmed or not identified. RESULTS: Of the 330 patients, 317 were evaluable. The mean age of patients was 39.63 years and 51.42% were women. The mean number of drugs used was 1.38, and 26.50% (95% CI, 21.94% -31.62%) patients were detected with Pharmacotherapy negative outcomes as a cause of visiting the Primary Care Emergency. 53.57% of the detected Pharmacotherapy negative outcomes detected as regards efficacy was 53.75%, 40.48% as regards need. More than three-quarters (77.41%; 95% CI, 67.35% -85.01%) of emergency visits caused by Pharmacotherapy negative outcomes were avoidable. In terms of severity, 92.86% of the Pharmacotherapy negative outcomes were mild. CONCLUSIONS: One in four Mula SUAP visits are due to a Pharmacotherapy negative outcomes, and 77.41% of them are preventable.

Unsaturated iridium pyridinedicarboxylate pincer complexes with catalytic activity in borylation of arenes.

Unsaturated σ,π-cyclooctenyl and hydrido Ir(III) complexes bearing an unusual tridentate dianionic ONO pincer-type ligand have been straightforwardly obtained from 2,6-pyridinedicarboxylic acid and standard Ir(I) starting materials. These complexes efficiently catalyzed the arene C-H borylation under thermal conditions.

Hydride mobility in trinuclear sulfido clusters with the core [Rh3(µ-H)(µ3-S)2]: molecular models for hydrogen migration on metal sulfide hydrotreating catalysts.

The treatment of [{Rh(µ-SH){P(OPh)(3)}(2)}(2)] with [{M(µ-Cl)(diolef)}(2)] (diolef=diolefin) in the presence of NEt(3) affords the hydrido-sulfido clusters [Rh(3)(µ-H)(µ(3)-S)(2)(diolef){P(OPh)(3)}(4)] (diolef=1,5-cyclooctadiene (cod) for 1, 2,5-norbornadiene (nbd) for 2, and tetrafluorobenzo[5,6]bicyclo[2.2.2]octa-2,5,7-triene (tfb) for 3) and [Rh(2)Ir(µ-H)(µ(3)-S)(2)(cod){P(OPh)(3)}(4)] (4). Cluster 1 can be also obtained by treating [{Rh(µ-SH){P(OPh)(3)}(2)}(2)] with [{Rh(µ-OMe)(cod)}(2)], although the main product of the reaction with [{Ir(µ-OMe)(cod)}(2)] was [RhIr(2)(µ-H)(µ(3)-S)(2)(cod)(2){P(OPh)(3)}(2)] (5). The molecular structures of clusters 1 and 4 have been determined by X-ray diffraction methods. The deprotonation of a hydrosulfido ligand in [{Rh(µ-SH)(CO)(PPh(3))}(2)] by [M(acac)(diolef)] (acac=acetylacetonate) results in the formation of hydrido-sulfido clusters [Rh(3)(µ-H)(µ(3)-S)(2)(CO)(2) (diolef)(PPh(3))(2)] (diolef=cod for 6, nbd for 7) and [Rh(2)Ir(µ-H)(µ(3)-S)(2)(CO)(2)(cod)(PPh(3))(2)] (8). Clusters 1-3 and 5 exist in solution as two interconverting isomers with the bridging hydride ligand at different edges. Cluster 8 exists as three isomers that arise from the disposition of the PPh(3) ligands in the cluster (cis and trans) and the location of the hydride ligand. The dynamic behaviour of clusters with bulky triphenylphosphite ligands, which involves hydrogen migration from rhodium to sulfur with a switch from hydride to proton character, is significant to understand hydrogen diffusion on the surface of metal sulfide hydrotreating catalysts.

Rational design of efficient rhodium catalysts for the anti-Markovnikov oxidative amination of styrene.

Cationic rhodium(I) complexes containing the flexible hemilabile phosphine ligand (3-ethoxypropyl)diphenylphosphine efficiently catalyzed the anti-Markovnikov oxidative amination of styrene in tetrahydrofurane at 80 degrees C to produce (E)-1-styrylpiperidine with turnover frequencies up to 75 h(-1) with excellent enamine selectivity (96%).

On the synthesis and chemical behaviour of the elusive bis(hydrosulfido)-bridged dinuclear rhodium(I) complexes [{Rh(mu-SH)(CO)(PR(3))}(2)].

Several bis(hydrosulfido)-bridged dinuclear rhodium(I) compounds, [{Rh(mu-SH)(L)(2)}(2)], have been prepared from rhodium(I) acetylacetonato complexes, [Rh(acac)(L)(2)], and H(2)S(g). Reaction of [Rh(acac){P(OPh)(3)}(2)] with H(2)S(g) affords the dinuclear bis(hydrosulfido)-bridged compound [{Rh(mu-SH){P(OPh)(3)}(2)}(2)] (1). However, reaction of complexes [Rh(acac)(CO)(PR(3))] with H(2)S(g) gives the dinuclear compound [{Rh(mu-SH)(CO)(PR(3))}(2)] (R=Cy, 2; R=Ph, 4) and the trinuclear cluster [Rh(3)(mu-H)(mu(3)-S)(2)(CO)(3)(PR(3))(3)] (R=Cy, 3; R=Ph, 5). The selective synthesis of both type of compounds has been carried out by control of the H(2)S(g) concentration in the reaction media. The trinuclear hydrido-sulfido cluster [Rh(3)(mu-H)(mu(3)-S)(2)(CO)(3)(PPh(3))(3)] (5) has been also obtained by reaction of [{Rh(mu-SH)(CO)(PPh(3))}(2)] (4) with [Rh(acac)(CO)(PPh(3))], proceeding through the trinuclear hydrosulfido-sulfido intermediate [Rh(3)(mu(3)-SH)(mu(3)-S)(CO)(3)(PPh(3))(3)]. The molecular structures of complexes 1 and 3 have been determined by X-ray diffraction methods. Compound 1 is stable in solution, but complexes 2 and 4 slowly transform in solution into the trinuclear hydrido-sulfido clusters 3 and 5, respectively, with the release of H(2)S(g) in a reversible way. (1)H NMR kinetic experiments for the transformation of 4 into 5 have revealed that this transformation follows second-order-type kinetic. The following activation parameters, DeltaH( not equal)=24+/-3 kJ mol(-1) and of DeltaS( not equal)=-223+/-8 J K(-1) mol(-1), have been calculated from the determination of the second-order rate constants in the temperature range 30-45 degrees C. The large negative value of the activation entropy is consistent with an associative character of the rate-determining step. A plausible multistep mechanism based on the chemical behaviour of hydrosulfido-metal complexes and compatible with the kinetic behaviour has been proposed.

Heavy metals removal from electroplating wastewater by aminopropyl-Si MCM-41.

The potential of removing nickel and copper from industrial electroplating wastewaters by using mesoporous materials with MCM-41 type structure functionalised with different ratios of aminopropyl groups, namely Na50, Na25 and Na5, were evaluated. The synthesised solids sorbents obtained were characterised by X-ray diffraction, elemental chemical analysis and IR spectroscopy. In preliminary experiments, studies were carried out to determine the optimal experimental conditions for the retention of heavy ions. Effects of concentration, optimal pH, interference with humic substances and other metals were studied for Na5, which showed the best capacity of absorption determined by the corresponding isotherm. This material has a greater selectivity against sodium, indicating that ionic strength does not affect the extraction. Results of an application of this material to remove nickel and copper in synthetic and real industrial wastewater samples from an electrochemical industry area are shown with successful results. The lowest level of nickel and copper were observed when Na5 was used. This observation suggests that reactive aminopropyl-Si MCM-41 and similar materials may be a promising and provide for alternative environmental technologies in the future.

Sequential C-H activation and dinuclear insertion of ethylene promoted by a diiridium complex.

Two ethylene molecules, bonded to different metal atoms of a diiridium(I) complex, can be converted into a bridging 3-butenyl-1-yl ligand and a terminal hydride. Such transformation is initiated by an ethylene C-H activation step and followed by an insertion of the second ethylene into a bridging vinyl ligand. This result illustrates the potentiality of diiridium(I) complexes to promote and support reaction sequences of alkene functionalization through C-H activation.