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The clinical implementation of magnetic hyperthermia has experienced little progress since the first clinical trial was completed in 2005. Some of the hurdles to overcome are the reliable production of magnetic nanoparticles with controlled properties and the control of the temperature at the target tissue in vivo. Here, forty samples of iron oxide superparamagnetic nanoparticles were prepared by similar methods and thoroughly characterized in terms of size, aggregation degree, and heating response. Selected samples were intratumorally administered in animals with subcutaneous xenografts of human pancreatic cancer. In vivo experiments showed that it is possible to control the rise in temperature by modulating the field intensity during in vivo magnetic hyperthermia protocols. The procedure does not require sophisticated materials and it can be easily implemented by researchers or practitioners working in magnetic hyperthermia therapies. [ABSTRACT FROM AUTHOR]

Advanced uses of smartphones are changing lifestyles, and may have a great impact in materials science in the near future. In this work, the use of these devices to develop fast, simple, and cheap methods to characterize magnetic nanoparticle suspensions is tested. A series of dilutions of a wide library of magnetic nanoparticles, composed of iron oxide materials in the range between 3 and 43 nm, with two different shapes and four different coatings is prepared. The colloid color is analyzed using the RGB (red, green, blue) color model. Ratios of these parameters are correlated with the suspension iron concentration and with the nanoparticles average size. A linear relationship between the color (in particular the G/R ratio) and both the colloid iron content and the particles size is found. The link between these parameters allows the development of two new methods to determine either the concentration or the particle size of magnetic nanoparticle suspensions just by acquiring images from suspensions of iron oxide magnetic nanoparticles with a smartphone. [ABSTRACT FROM AUTHOR]

The kinetics of the equilibria between all of the participating trans-[Ni[Rf.sub.2][L.sub.2]] (Rf = 3,5-[C.sub.5][Cl.sub.2][F.sub.3], L = group of 15 soft monodentate weak ligand as Sb[Ph.sub.3] or As[Ph.sub.3]) species are studied by [super 19]F exchange spectroscopy experiments and the exchange rates and rate constants are calculated. The obtained data have revealed the weakness of acetone compared to water and As[Ph.sub.3] and this is the first data that is available for square-planar nickel(II) aquacomplexes.

Abstract: Magnetic nanoparticles (M:NPs) are unique agents for in vivo thermal therapies due to their multimodal capacity for efficient heat generation under optical and/or magnetic excitation. Nevertheless, their transfer from laboratory to the clinic is hampered by the absence of thermal feedback and by the influence that external conditions (e.g., agglomeration and biological matrix interactions) have on their heating efficiency. Overcoming these limitations requires, first, the implementation of strategies providing thermal sensing to M:NPs in order to obtain in situ thermal feedback during thermal therapies. At the same time, M:NPs should be modified so that their heating efficiency will be maintained independently of the environment and the added capability for thermometry. In this work, optomagnetic hybrid nanostructures (OMHSs) that simultaneously satisfy these two conditions are presented. Polymeric encapsulation of M:NPs with neodymium‐doped nanoparticles results in a hybrid structure capable of subtissue thermal feedback while making the heating efficiency of M:NPs independent of the medium. The potential application of the OMHSs herein developed for fully controlled thermal therapies is demonstrated by an ex vivo endoscope‐assisted controlled intracoronary heating experiment. [ABSTRACT FROM AUTHOR]

The first experimental observations on the transmetalation in a Negishi coupling are reported. The unexpected complications that arose from such transmetalation are discussed.

This work reports the synthesis of surface-modified iron oxide magnetic nanotubes (FeONT) with poly(amido amine) dendrimers of the third generation (PAMAM-G3) as novel nanomaterials for potential drug-delivery applications. FeONT were obtained by reduction of α-FeO nanotubes, which were synthesized following a hydrothermal strategy using SO /HPO to control the size and morphology of the prepared materials. FeONT were further functionalized with PAMAM-G3 moieties using a silane coupling agent. Pristine and PAMAM-modified FeONT were characterized through TEM, FTIR, XRD, N adsorption-desorption isotherms and VSM measurements, which confirmed the nanotubular morphology and magnetic behavior for both systems, and TGA analyses, which revealed a PAMAM grafting percentage of 16.8%. The effect of PAMAM conjugation on the adsorption and release properties of FeONT was examined using silibinin as model poorly soluble drug compound. Our results revealed that PAMAM grafting increased the maximum amount of adsorbed drug from 675 mg g in pristine FeONT to 825 mg g in PAMAM-FeONT. These quantities exceed by far the drug-loading capacity of other pristine and PAMAM-modified nanotubular systems, which constitutes a relevant outcome for the present study. [ABSTRACT FROM AUTHOR]

In addition to the expected products, trans- and cis-[PdRfMe(PPh3)2], the transmetalation between ZnMe2 and trans-[PdRfCl(PPh3)2] yields [PdMeCl(PPh3)2] and ZnRfMe as the result of secondary transmetalation processes. ZnRfMe is also formed by reaction of trans- and cis-[PdRfMe(PPh3)2] with ZnMe2. The different competitive reaction mechanisms that participate in the transmetalations have been studied by experiments and by DFT calculations. The relative contribution of each reaction pathway in the formation of the unwanted product ZnRfMe has been measured. The effect of excess ligand (PPh3) on the several transmetalations has been established. [ABSTRACT FROM AUTHOR]

In recent years, magnetic nanoparticles have been widely investigated due to their potential in biomedical applications. For successful in vivo applications, magnetic nanoparticles must satisfy several requirements such as biocompatibility, invisibility to the immune system, high colloidal stability in biological fluids, and long blood circulation times. In this study, we have developed a formulation in which the magnetic nanoparticles are coated with bovine serum albumin to provide enhanced colloidal stability in biological fluids preserving their magnetic properties. In addition, the nanoparticles carry a chemotherapeutic drug, showing their potential as drug delivery systems. Our results reveal the influence of protein adsorption on the colloidal stability and the dynamical magnetic response of functionalized magnetic nanoparticles. Moreover, cellular internalization and in vitro cytotoxic activity in Panc-1 pancreatic cancer cells reveal enhanced cellular internalization, successful intracellular drug delivery, and efficient anticancer activity. [ABSTRACT FROM AUTHOR]

This work reports on the study of three samples of 8 nm Co-ferrite particles prepared by standard methods based on the thermal decomposition of metal–organic precursors. Although all samples are single phase according to conventional techniques of structural and chemical characterization, they show strongly sample-dependent magnetic properties ranging from bulk-like ferrimagnetism to glassy magnetic behaviour. We show that the presence of crystallite domains associated with crystallographic defects throughout the particles leads to highly-frustrated ferrimagnetic cores that are responsible for the glassy phenomenology, while only samples almost free of structural imperfections show bulk-like magnetic properties. These results suggest the key role of the crystal quality in the large variability of magnetic properties previously reported for Co-ferrite nanoparticles. Besides, achieving control of the amount of structural defects in monodisperse, stoichiometric Co-ferrite nanoparticles can be an additional nano-structuring procedure to tailor their final magnetic properties. [ABSTRACT FROM AUTHOR]

Superparamagnetic iron oxide nanoparticles (SPION) have shown potential as multifunctional nanoparticles for theranostic applications. The assessment of toxicity and biocompatibility of the tailored product is, therefore, paramount to deliver commercially sound theranostic tools. In this study, a systematic approach to testing the cytotoxicity of three differently coated SPIONs derived from two synthesis methods (co-precipitation in water and thermal decomposition), with different coatings, and surface charges has been carried out. Toxicity and biocompatibility were investigated by automated high content screening of two breast cancer cell lines (MCF7, and BT474) and healthy (MCF10A) control exposed to incremental doses of the SPIONs up to 24 h in vitro. In the case of iron oxide coated with aminodextran (ADNH), this elicited pronounced effects on the permeability of BT474 with reflected evidence on the cell count reduction and lysosomal mass when compared to the aminopropylsilane (ASi), dimercaptosuccininc acid (DMSA/OD10) coated particles. More subtle effect was observed in the cell count of MCF7 cell line at the highest concentration of ADNH coated nanoparticle. Therefore, from the three cell lines used in this study it is possible to evince subtleness in the cell-specific cytotoxicity response. [ABSTRACT FROM AUTHOR]

The influence of the nature of two different ionic liquids, namely 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C1C4Im][NTf2], and 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide, [C1C1C4Im][NTf2], on the catalytic hydrogenation of 1,3-cyclohexadiene with [Rh(COD)(PPh3)2][NTf2] (COD=1,5-cyclooctadiene) was studied. Initially, the effect of different concentrations of 1,3-cyclohexadiene on the molecular interactions and on the structure in two ionic liquids was investigated by NMR and by molecular dynamic simulations. It was found that in both ionic liquids 1,3-cyclohexadiene is solvated preferentially in the lipophilic regions. Furthermore, the higher solubility of 1,3-cyclohexadiene in [C1C4Im][NTf2] and the smaller positive values of the excess molar enthalpy of mixing for the 1,3-cyclohexadiene [C1C4Im][NTf2] system in comparison with 1,3-cyclohexadiene [C1C1C4Im][NTf2] indicate more favorable interactions between 1,3-cyclohexadiene and the C1C4Im熫抢 than with the C1C1C4Im熫抢. Subsequently, diffusivity and conductivity measurements of the 1,3-cyclohexadiene ionic liquid mixtures at different compositions allowed a characterization of mass and charge transport in the media and access to the ionicity of ionic liquids in the mixture. From the dependence of the ratio between molar conductivity and the conductivity inferred from NMR diffusion measurements, Λimp/ΛNMR, on concentration of 1,3-cyclohexadiene in the ionic liquid mixture, it was found that increasing the amount of 1,3-cyclohexadiene leads to a decrease in the ionicity of the medium. Finally, the reactivity of the catalytic hydrogenation of 1,3-cyclohexadiene using [Rh(COD)(PPh3)2][NTf2] performed in [C1C4Im][NTf2] at different compositions of 1,3-cyclohexadiene and in [C1C1C4Im][NTf2] at one composition was related linearly to the viscosity, hence the reaction rate is determined by the mass transport properties of the media. [ABSTRACT FROM AUTHOR]

Ionic liquids are a stabilizing medium for the in situsynthesis of ruthenium nanoparticles. Herein we show that the addition of molecular polar solutes to the ionic liquid, even in low concentrations, eliminates the role of the ionic liquid 3D structure in controlling the size of ruthenium nanoparticles, and can induce their aggregation. We have performed the synthesis of ruthenium nanoparticles by decomposition of [Ru(COD)(COT)] in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C1C4Im][NTf2], under H2in the presence of varying amounts of water or 1-octylamine. For water added during the synthesis of metallic nanoparticles, a decrease of the solubility in the ionic liquid was observed, showed by nanoparticles located at the interface between aqueous and ionic phases. When 1-octylamine is present during the synthesis, stable nanoparticles of a constant size are obtained. When 1-octylamine is added after the synthesis, aggregation of the ruthenium nanoparticles is observed. In order to explain these phenomena, we have explored the molecular interactions between the different species using 13C-NMR and DOSY (Diffusional Order Spectroscopy) experiments, mixing calorimetry, surface tension measurements and molecular simulations. We conclude that the behaviour of the ruthenium nanoparticles in [C1C4Im][NTf2] in the presence of 1-octylamine depends on the interaction between the ligand and the nanoparticles in terms of the energetics but also of the structural arrangement of the amine at the nanoparticle's surface. [ABSTRACT FROM AUTHOR]

Iron oxide nanoparticles (IONPs) are suitable materials for contrast enhancement in magnetic resonance imaging (MRI). Their potential clinical applications range from diagnosis to therapy and follow-up treatments. However, a deeper understanding of the interaction between IONPs, culture media and cells is necessary for expanding the application of this technology to different types of cancer therapies. To achieve new insights of these interactions, a set of IONPs were prepared with the same inorganic core and five distinct coatings, to study their aggregation and interactions in different physiological media, as well as their cell labelling efficiency. Then, a second set of IONPs, with six different core sizes and the same coating, were used to study how the core size affects cell labelling and MRI in vitro. Here, IONPs suspended in biological media experience a partial removal of the coating and adhesion of molecules. The FBS concentration alters the labelling of all types of IONPs and hydrodynamic sizes ≥ 300 nm provide the greatest labelling using the centrifugation-mediated internalization (CMI). The best contrast for MRI results requires a core size range between 12–14 nm coated with dimercaptosuccinic acid (DMSA) producing R2* values of 393.7 s−1 and 428.3 s−1, respectively. These findings will help to bring IONPs as negative contrast agents into clinical settings. [ABSTRACT FROM AUTHOR]

Simple Summary: In this work, a smart gemcitabine delivery system based on magnetic nanoparticles (MNP) is proposed. Gemcitabine (GEM) is a chemotherapeutic agent usually employed as monotherapy for the treatment of pancreatic cancer. Unfortunately, this drug presents short half-life and high toxicity in non-tumoral tissues. Thus, new efficient drug delivery systems are needed. In this regard, we modified MNP to attach this drug via disulfide bonds (MNP-GEM) to promote the selective release of GEM in pancreatic cancer cells, and the great potential of our proposed nanocarrier for biomedical applications is broadly assessed. Remarkably, this modification has proved to prevent the unspecific binding of proteins, reduced the cytotoxic effect of the drug in non-cancerous cells, improved the internalization in pancreatic cancer cells, and its activity was synergistically enhanced in combination with magnetic hyperthermia. Magnetic nanoparticles (MNP) are employed as nanocarriers and in magnetic hyperthermia (MH) for the treatment of cancers. Herein, a smart drug delivery system composed of MNP functionalized with the cytotoxic drug gemcitabine (MNP-GEM) has been thoroughly evaluated. The linker employed is based on a disulfide bond and allows the controlled release of GEM under a highly reducing environment, which is frequently present in the cytoplasm of tumor cells. The stability, MH, and the interaction with plasma proteins of the nanoparticles are evaluated, highlighting their great potential for biological applications. Their cytotoxicity is assessed in three pancreatic cancer cell lines with different sensitivity to GEM, including the generation of reactive oxygen species (ROS), the effects on the cell cycle, and the mechanisms of cell death involved. Remarkably, the proposed nanocarrier is better internalized than unmodified nanoparticles, and it is particularly effective in PANC-1 cells, resistant to GEM, but not in non-tumoral keratinocytes. Additionally, its combination with MH produces a synergistic cytotoxic effect in all cancer cell lines tested. In conclusion, MNP-GEM presents a promising potential for treating pancreatic cancer, due to multiple parameters, such as reduced binding to plasma proteins, increased internalization, and synergistic activity when combined with MH. [ABSTRACT FROM AUTHOR]

The article focuses on the impact of nucleophile to various cross-coupling reactions when used for transmetalation. One of the types of coupling reactions is the Negishi reaction which it has two kinds of organometallic reagent. The mentioned reagent can be used depending on the protocol. The transmetalation step in Negishi coupling is speculative and its essential stereochemical and kinetic aspects remain obscure.

Immunotherapy has emerged as a promising strategy to eradicate cancer cells. Particularly, the development of cancer vaccines to induce a potent and sustained antigen-specific T cell response has become a center of attention. Herein, we describe a novel immunotherapy based on magnetic nanoparticles (MNP) covalently modified with the OVA 254-267 antigen and a CpG oligonucleotide via disulfide bonds. The MNP-CpG-COVA significantly enhances dendritic cell activation and CD8 + T cell antitumoral response against B16-OVA melanoma cells in vitro . Notably, the immune response induced by the covalently modified MNP is more potent and sustained over time than that triggered by the free components, highlighting the advantage of nanoformulations in immunotherapies. What is more, the nanoparticles are stable in the blood after in vivo administration and induce potent levels of systemic tumor-specific effector CD8 + T cells. Overall, our findings highlight the potential of covalently functionalized MNP to induce robust immune responses against mouse melanoma., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors. Published by Elsevier Ltd.)

The new and unique possibilities that nanomaterials offer have greatly impacted biomedicine, from the treatment and diagnosis of diseases, to the specific and optimized delivery of therapeutic agents. Technological advances in the synthesis, characterization, standardization, and therapeutic performance of nanoparticles have enabled the approval of several nanomedicines and novel applications. Discoveries continue to rise exponentially in all disease areas, from cancer to neurodegenerative diseases. In Spain, there is a substantial net of researchers involved in the development of nanodiagnostics and nanomedicines. In this review, we summarize the state of the art of nanotechnology, focusing on nanoparticles, for the treatment of diseases in Spain (2017-2022), and give a perspective on the future trends and direction that nanomedicine research is taking., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Fernández-Gómez, Pérez de la Lastra Aranda, Tosat-Bitrián, Bueso de Barrio, Thompson, Sot, Salas, Somoza, Espinosa, Castellanos and Palomo.)

Magnetic nanoparticles (MNPs), and in particular iron oxide nanoparticles (mainly magnetite and maghemite), are being widely used in the form of aqueous colloids for biomedical applications. In such colloids, nanoparticles tend to form assemblies, either aggregates, if the union is permanent, or agglomerates, if it is reversible. These clustering processes have a strong impact on the MNPs' properties that are often not well understood. In this review, the causes and consequences of MNPs aggregation/agglomeration are reviewed and discussed. Special attention has been paid to the impact of the MNPs aggregation/agglomeration on their magnetic properties and heating properties, when exposed to an alternating magnetic field in the frame of magnetic hyperthermia. In addition, a model system with MNPs of two different sizes coated with three different molecules oleic acid, meso-2, 3-dimercaptosuccinic acid and poly(maleic anhydride-alt-1-octadecene) has been characterized and the results used to support the ideas reviewed.

Breakthroughs in nanotechnology have made it possible to integrate different nanoparticles in one single hybrid nanostructure (HNS), constituting multifunctional nanosized sensors, carriers, and probes with great potential in the life sciences. In addition, such nanostructures could also offer therapeutic capabilities to achieve a wider variety of multifunctionalities. In this work, the encapsulation of both magnetic and infrared emitting nanoparticles into a polymeric matrix leads to a magnetic-fluorescent HNS with multimodal magnetic-fluorescent imaging abilities. The magnetic-fluorescent HNS are capable of simultaneous magnetic resonance imaging and deep tissue infrared fluorescence imaging, overcoming the tissue penetration limits of classical visible-light based optical imaging as reported here in living mice. Additionally, their applicability for magnetic heating in potential hyperthermia treatments is assessed.

Nanotechnology plays an increasingly important role in the biomedical arena. Iron oxide nanoparticles (IONPs)-labelled cells is one of the most promising approaches for a fast and reliable evaluation of grafted cells in both preclinical studies and clinical trials. Current procedures to label living cells with IONPs are based on direct incubation or physical approaches based on magnetic or electrical fields, which always display very low cellular uptake efficiencies. Here we show that centrifugation-mediated internalization (CMI) promotes a high uptake of IONPs in glioblastoma tumour cells, just in a few minutes, and via clathrin-independent endocytosis pathway. CMI results in controllable cellular uptake efficiencies at least three orders of magnitude larger than current procedures. Similar trends are found in human mesenchymal stem cells, thereby demonstrating the general feasibility of the methodology, which is easily transferable to any laboratory with great potential for the development of improved biomedical applications.

Iron oxide nanoparticles with engineered physical and biochemical properties are finding a rapidly increasing number of biomedical applications. However, a wide variety of safety concerns, especially those related to oral exposure, still need to be addressed for iron oxide nanoparticles in order to reach clinical practice. Here, we report on the effects of chronic oral exposure to low doses of γ-Fe2O3 nanoparticles in growing chickens. Animal observation, weight, and diet intake reveal no adverse signs, symptoms, or mortality. No nanoparticle accumulation was observed in liver, spleen, and duodenum, with feces as the main excretion route. Liver iron level and duodenal villi morphology reflect the bioavailability of the iron released from the partial transformation of γ-Fe2O3 nanoparticles in the acid gastric environment. Duodenal gene expression studies related to the absorption of iron from γ-Fe2O3 nanoparticles indicate the enhancement of a ferric over ferrous pathway supporting the role of mucins. Our findings reveal that oral administration of iron oxide nanoparticles is a safe route for drug delivery at low nanoparticle doses.

The final goal in magnetic hyperthermia research is to use nanoparticles in the form of a colloidal suspension injected into human beings for a therapeutic application. Therefore the challenge is not only to develop magnetic nanoparticles with good heating capacities, but also with good colloidal properties, long blood circulation time and with grafted ligands able to facilitate their specific internalisation in tumour cells. Significant advances have been achieved optimising the properties of the magnetic nanoparticles, showing extremely large specific absorption rate values that will contribute to a reduction in the concentration of the magnetic fluid that needs to be administered. In this review we show the effect of different characteristics of the magnetic particles, such as size, size distribution and shape, and the colloidal properties of their aqueous suspensions, such as hydrodynamic size and surface modification, on the heating capacity of the magnetic colloids.

Suspensions of small sized (1-2.5 nm) ruthenium nanoparticles (RuNPs) have been obtained by decomposition, under H(2), of (η(4)-1,5-cyclooctadiene)(η(6)-1,3,5-cyclooctatriene)ruthenium(0), [Ru(COD)(COT)], in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C(1)C(4)Im][NTf(2)], and in the presence of different compounds acting as ligands: C(8)H(17)NH(2), PPhH(2), PPh(2)H and H(2)O. Previous and new liquid NMR experiments showed that the ligands are coordinated or in the proximity to the surface of the RuNPs. Herein is reported how the ligand affects the catalytic performance (activity and selectivity) compared to a ligand-free system of RuNPs, when RuNPs in [C(1)C(4)Im][NTf(2)] are used as catalysts for the hydrogenation of various unsaturated compounds (1,3-cyclohexadiene, limonene and styrene). It has been observed that σ-donor ligands increase the activity of the nanoparticles, contrarily to π-acceptor ones.

The influence of the nature of two different ionic liquids, namely 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C(1)C(4)Im][NTf(2)], and 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide, [C(1)C(1)C(4)Im][NTf(2)], on the catalytic hydrogenation of 1,3-cyclohexadiene with [Rh(COD)(PPh(3))(2)][NTf(2)] (COD = 1,5-cyclooctadiene) was studied. Initially, the effect of different concentrations of 1,3-cyclohexadiene on the molecular interactions and on the structure in two ionic liquids was investigated by NMR and by molecular dynamic simulations. It was found that in both ionic liquids 1,3-cyclohexadiene is solvated preferentially in the lipophilic regions. Furthermore, the higher solubility of 1,3-cyclohexadiene in [C(1)C(4)Im][NTf(2)] and the smaller positive values of the excess molar enthalpy of mixing for the 1,3-cyclohexadiene + [C(1)C(4)Im][NTf(2)] system in comparison with 1,3-cyclohexadiene + [C(1)C(1)C(4)Im][NTf(2)] indicate more favorable interactions between 1,3-cyclohexadiene and the C(1)C(4)Im(+) cation than with the C(1)C(1)C(4)Im(+) cation. Subsequently, diffusivity and conductivity measurements of the 1,3-cyclohexadiene + ionic liquid mixtures at different compositions allowed a characterization of mass and charge transport in the media and access to the ionicity of ionic liquids in the mixture. From the dependence of the ratio between molar conductivity and the conductivity inferred from NMR diffusion measurements, Λ(imp)/Λ(NMR), on concentration of 1,3-cyclohexadiene in the ionic liquid mixture, it was found that increasing the amount of 1,3-cyclohexadiene leads to a decrease in the ionicity of the medium. Finally, the reactivity of the catalytic hydrogenation of 1,3-cyclohexadiene using [Rh(COD)(PPh(3))(2)][NTf(2)] performed in [C(1)C(4)Im][NTf(2)] at different compositions of 1,3-cyclohexadiene and in [C(1)C(1)C(4)Im][NTf(2)] at one composition was related linearly to the viscosity, hence the reaction rate is determined by the mass transport properties of the media.

Very stable suspensions of small sized (c.a. 1.2 nm) and homogeneously dispersed ruthenium nanoparticles (RuNPs) were obtained by decomposition, under H(2), of (η(4)-1,5-cyclooctadiene)(η(6)-1,3,5-cyclooctatriene)ruthenium(0), [Ru(COD)(COT)], in various imidazolium derived ionic liquids (ILs: [RMIm][NTf(2)] (R = C(n)H(2n+1) where n = 2; 4; 6; 8; 10) and in the presence of amines as ligands (1-octylamine, 1-hexadecylamine). These nanoparticles were compared to others stabilized either in pure ILs or by the same ligands in THF. NMR experiments ((13)C solution and DOSY) demonstrate that the amines are coordinated to the surface of the RuNPs. These RuNPs were investigated for the hydrogenation of aromatics and have shown a high level of recyclability (up to 10 cycles) with neither loss of activity nor significant agglomeration.

The enthalpy for the substitution reaction cis-[PdRf(2)(THF)(2)] + 2 L -->cis-[PdRf(2)L(2)] + 2THF (THF = tetrahydrofuran) has been measured in THF by calorimetric methods for Rf = 3,5-dichloro-2,4,6-trifluorophenyl, L = PPh(3), AsPh(3), SbPh(3), PMePh(2), PCyPh(2), PMe(3), AsMePh(2), or L(2) = dppe (1,2-bis(diphenylphosphino)ethane), dppf (1,1'-bis(diphenylphosphino)ferrocene). The values determined show that the substitution enthalpy has a strong dependence on the electronic and steric properties of the ligand. The study of the consecutive substitution reactions cis-[PdRf(2)(THF)(2)] + L -->cis-[PdRf(2)L(THF)] + THF, and cis-[PdRf(2)L(THF)] + L -->cis-[PdRf(2)L(2)] + THF has been carried our for L = PPh(3) and L = PCyPh(2). The first substitution is clearly more favorable for the bulkier leaving ligand, but the second gives practically the same DeltaH value for both cases, indicating that the differences in steric hindrance happen to compensate the electronic differences for both ligands. The X-ray structures of cis-[PdRf(2)(PMePh(2))(2)], cis-[PdRf(2)(dppe)] and cis-[PdRf(2)(dppf)] are reported.

A recent claimed spectroscopic observation (by (1)H NMR) of 14-electron T-shaped 3-coordinated palladium complexes turns out to be a misinterpretation. A thorough study of the species formed by [PdRX(AsPh(3))(2)] (R=Ph, C(6)Cl(2)F(3); X=Cl, I) in different solvents (S=CDCl(3), THF, DMF) suggests that: 1) there is no NMR-detectable amount of [PdRX(AsPh(3))], and 2) in the presence of free arsine (AsPh(3)/[PdRX(AsPh(3))(2)] 2:1) the concentration of [PdRX(AsPh(3))(S)] is negligible. This clearly settles matters in the controversy of dissociative or associative pathways for the transmetalation step involved in the Stille coupling in favor of the latter: under catalytic conditions the dominant pathway is the associative reaction of the stannane with the square-planar complex [PdRX(AsPh(3))(2)].