Examination of Indium Triphospholyls as Precursors for Nanoparticle Synthesis

The synthesis and characterization of the new compounds K(P3C2R2) [R=Ad (2), sBu (3)] and In(P3C2R2) [R=Ad (4), Mes (5)] are described. Further, the synthesis of indium nanoparticles via a single‐source precursor approach using In(1,2,4‐P3C2tBu2) (1) as precursor is reported. These nanoparticles were characterized by TEM, HRTEM, EDX, XRD, NMR, and optical spectroscopy. New compounds of the type M(1,2,4‐P3C2R2) (M=K, In, R=Ad, sBu, Mes) were synthesized, characterized, and examined in view of their use as precursors for indium‐based nanoparticles

Stoichiometry-controlled FeP nanoparticles synthesized from a single source precursor

Phase-pure FeP nanoparticles (NPs) have been synthesized through low temperature thermolysis of the single source precursor [(CO)4Fe(PH3)]. Examination of the mechanism demonstrates the central role of the labile CO ligands and the weak P–H bonds to yield stoichiometry controlled FeP materials

Silver-Catalyzed C-C Bond Formation between Methane and Ethyl Diazoacetate in Supercritical CO2

Even in the context of hydrocarbons’ general resistance to selective functionalization, methane’s volatility and strong bonds pose a particular challenge. We report here that silver complexes bearing perfluorinated indazolylborate ligands catalyze the reaction of methane (CH4) with ethyl diazoacetate (N2CHCO2Et) to yield ethyl propionate (CH3CH2CO2Et). The use of supercritical carbon dioxide (scCO2) as the solvent is key to the reaction’s success. Although the catalyst is only sparingly soluble in CH4/CO2 mixtures, optimized conditions presently result in a 19% yield of ethyl propionate (based on starting quantity of the diazoester) at 40°C over 14 hours.Ministerio de Ciencia e Innovación (grants CTQ2008-00042-BQU, CTQ2007-65251-BQU, and CTQ2007-30762-E), the European Research Area Chemistry Programme (2nd call “Chemical activation of carbon dioxide and methane” contract no. 1736154), the Consolider Ingenio 2010 (grants CSD2006-003 and CSD2007-00006), the Institut de Chimie of the CNRS, the Junta de Andalucía (P07-FQM-2870), and the Generalitat Velenciana (ACOMP/2010/155).We dedicate this work to Professor Ernesto Carmona. Support for this work was provided by the Ministerio de Ciencia e Innovacion (grants CTQ2008-00042-BQU, CTQ2007-65251-BQU, and CTQ2007-30762-E), the European Research Area Chemistry Programme (2nd call "Chemical activation of carbon dioxide and methane" contract no. 1736154), the Consolider Ingenio 2010 (grants CSD2006-003 and CSD2007-00006), the Institut de Chimie of the CNRS, the Junta de Andalucia (P07-FQM-2870), and the Generalitat Velenciana (ACOMP/2010/155). We thank the Servicio Central de Soporte a la Investigacion Experimental (Universidad de Valencia) for access to the instrumental facilities and J. de la Rosa and A. Sanchez de la Campa (Universidad de Huelva) for ICP-MS analyses

Contribution à l'étude de complexes organométalliques dinucléaires du molybdène à environnement soufré pour l'activitaion moléculaire (réactivité vis à vis d'alcynols, d'isocyanures et de molécules soufrées)

Les complexes organométalliques possédant un environnement soufré font l objet, depuis plusieurs années, de nombreuses études qui ont démontré les capacités de ces dérivés à activer de nombreux substrats organiques ou inorganiques. Les travaux qui ont été menés au cours de cette thèse s inscrivent dans la continuité du développement de la chimie des systèmes dimolybdène thiolato-pontés {Mo2Cp2( -SMe)n}+ (n=2,3) qui est réalisée dans le laboratoire afin d évaluer l apport de ces systèmes pour l activation moléculaire. Dans une première partie, nous présentons nos résultats concernant la coordination et la transformation d alcools propargyliques par le complexe [Mo2Cp2( -SMe)3(CH3CN)2] (BF4). Nous décrivons la synthèse puis la transformation de composés -alcyne en complexes -allénylidène. La réactivité des dérivés -allénylidène avec des agents nucléophiles ainsi que les réactions de transferts successifs d hydrures et de protons sur ces dérivés sont également décrites. Le second chapitre du manuscrit est consacré à la transformation de ligands isocyanure par action de réactifs basiques ou/et nucléophiles comme NaOH, NaSH et NaCCH. En particulier, des réactions permettant l obtention, via des processus impliquant la formation de liaisons C-C, C-N ou C-O, d espèces comportant des ligands alkylidyne et amino-oxycarbène sont décrites. La troisième partie de ce travail concerne la réactivité du complexe [Mo2Cp2( -SMe)3(CH3CN)2](BF4) avec des molécules hétérocycliques soufrées. Des transformations mettant enjeu la substitution des ligands acétonitrile mais également la formation et la rupture de liaisons C-S ont été mises en évidence. L ensemble de ces résultats montre la richesse et l originalité des systèmes du dimolybdène utilisés.We have been involved for some years in sulfur rich bimetallic systems which can act as models of species occuring in biological and industrial processes. Our approach implied organometallic complexes containing the bimetallic core {Mo2Cp2( -SMe)3}, which react with unsatured molecules such as alkyne, isocyanide, nitrile... Complexes with alkynol ligands bridging two metals have been isolated and characterised. Further transformations of Mo2-alkynol adducts to allenylidene species were also obtained, and the conversion of the former into an agostic ligand was observed. At the same time, we described the reactivity of isonitrile towards nucleophilic agents (NaOH, NaSH or NaCCH), leading to new compound containing ligands such as aminocarbyne, aminocarbene and aminooxycarbene which result either from C-C and C-N couplings between the cyclopentadienyl ligand and isocyanides or from C-C coupling between isocyanide groups. Moreover, the syntheses and characterisation of Mo complexes containing sulfide, thioether, dithiane and thioxane were carried out. These reactions are of interest in connection with the modeling of catalytic hydrodesulfuration (HDS) processes. Finally, we described here the syntheses of new complexes and original transformations promoted by a bimetallic molybdenum core.BREST-BU Droit-Sciences-Sports (290192103) / SudocSudocFranceF

Carbon−Sulfur and Carbon−Halogen Bond Cleavage of Acyclic or Cyclic Thioethers, Thiophenes, and Dihaloalkanes with the Trithiolato-Bridged Cation [Mo 2 Cp 2 (μ-SMe) 3 (MeCN) 2 ] +

International audienceReactions of the trithiolato-bridged complex [Mo2Cp2(μ-SMe)3(MeCN)2](BF4) (1) with acyclic (e.g., Et2S) or cyclic (e.g., thiirane, thietane, tetrahydrothiophene, 1,4-dithiane, and 1,4-thioxane) thioethers and chalcogenophenes (benzothiophene, benzoselenophene, and dibenzothiophene) in dihaloalkanes led to either the thioether- and halide-bridged compounds [Mo2Cp2(μ-SMe)2(μ-SRR′)(μ-X)](BF4) (R = R′ = Et, X = Cl (3); RR′ = C4H8, X = Cl (10), X = Br (11) ; RR′ = C4H8O, X = Cl (14)), and dithioether- and chloro-bridged derivatives [Mo2Cp2(μ-SMe)2(μ-Cl){μ-κ1(S),κ1(S)-(SR′′x(CH2)nSR′′x}](BF4) (x = 1, R′′ = Me, n = 1 (4); x = 0, n = 4 (13)) or the μ-sulfido complex [Mo2Cp2(μ-SMe)3(μ-S)](BF4) (6) and the methyl 1,3-propylthiolate thioether-bridged compound [Mo2Cp2(μ-SMe)2{μ-κ2(S),κ2(S)-S(CH2)3SMe}](BF4) (8), according to the structural features of the organic sulfur reagents. Ring-opening reaction through the cleavage of C−S bonds occurred when small-ring thioethers (e.g., thiirane and thietane) are used as reagents, whereas facile C−X (X = Cl, Br) bond cleavage was observed for other sulfur molecules. Some reactions that were conducted in chlorocarbon solvents (e.g., CH2Cl2, (CH2)2Cl2) gave rise to the formation of the oxo-bridged complex [Mo2Cp2(μ-SMe)3(μ-O)](BF4) (7) as a byproduct with moderate yields. All new complexes have been characterized by elemental analyses and spectroscopic methods, supplemented for the tetraphenylborate or hexafluorophosphate salts of 4, 6−8, 10, and 13 by X-ray diffraction

C−C, C−S, and C−N Coupling versus Dealkylation Processes in the Cationic Tris(thiolato)dimolybdenum(III) Complexes [Mo 2 Cp 2 (μ-SMe) 3 L 2 ] + (L = xylNC, t -BuNC, CO, MeCN)

International audienceReductive coupling between isocyanide ligands attached to adjacent molybdenum atoms in the bis(aryl isocyanide) complex [Mo2Cp2(μ-SMe)3(xylNC)2](BF4) (1) was initiated by addition of the hydrosulfide anion (HS−) to 1 under reflux in tetrahydrofuran, affording, in nearly quantitative yields, the dimetallaimidoyl(amino)carbene derivative [Mo2Cp2(μ-SMe)3{μ-η1(C):η1(C)-C(NHxyl)C(Nxyl)}] (7), in which both isocyanide groups of 1 are now linked by a new C−C bond. When the previous reaction was conducted in the presence of a large excess of hydrosulfide (20 equiv), under similar experimental conditions, the dithiocarbonimidate compound [Mo2Cp2(μ-SMe)2(μ-S2CNxyl)] (8) was obtained in quantitative yields. This product results from subsequent thiolate exchange and substitution reactions to afford a quadruply sulfur bridged intermediate, followed by free isonitrile addition to sulfido S atoms. Treatment of the coupled isocyanide derivative 7 with HBF4 led exclusively to the formation of the starting complex 1 by reversible isocyanide ligand decoupling. The heating of a tetrahydrofuran solution of 1 with the base NaC≡CH gave, in high yields, the μ-alkylidyne and μ-acetylide product [Mo2Cp(μ-SMe)2{μ-(η5-C5H4)(xylN)CN(xyl)C}(μ-CCH)] (9), in which a deprotonated Cp and both isocyanide ligands of 1 are now linked by new C−C and C−N bonds, and in addition an acetylide has replaced a thiolate ligand of 5. Reaction of the μ-alkylidyne complex [Mo2Cp(μ-SMe)3{μ-(η5-C5H4)(xylN)CN(xyl)C}] (5) with NaC≡CH under reflux in tetrahydrofuran produced, in high yields, the μ-alkylidyne and bis(μ-acetylide) cationic compound [Mo2Cp(μ-SMe)2{μ-(η5-C5H4)(xylN)CN(xyl)C}(μ-CCH)2]Br (10), in which two xylNC ligands have replaced a thiolate group of 5. Further reactions of the bis(μ-isocyanide) complex 10 with NaOH (suspension), on the one hand, and HBF4, on the other hand, under reflux in tetrahydrofuran or at room temperature in dichloromethane, respectively, led to the formation in high yields of the known mixed μ-alkylidyne and μ-amino-oxycarbene species [Mo2Cp(μ-SMe)2{μ-(η5-C5H4)(xylN)CN(xyl)C}{μ-η1(O):η1(C)-OCNHxyl}] (12) and the new tetrakis(isocyanide) dicationic derivative [Mo2Cp2(μ-SMe)2(xylNC)4](BF4)2 (11), respectively. The latter complex results from successive protonation at one carbon atom of the cyclopentadienyl ligand linked with isocyanides of 10 and decoupling between deprotonated Cp and isocyanide ligands. The heating of a tetrahydrofuran solution of a mixture of the bis(alkyl isocyanide) complex [Mo2Cp2(μ-SMe)3(t-BuNC)2](BF4) (2) and NaSH proceeded exclusively through the dealkylation of one tert-butyl isocyanide ligand to afford the known product [Mo2Cp2(μ-SMe)3(t-BuNC)](CN)] (13). Similar reaction of the dicarbonyl derivative [Mo2Cp2(μ-SMe)3(CO)2]Cl (3) with NaSH proceeded through dealkylation of one thiolate group to yield the new neutral sulfido species [Mo2Cp2(μ-SMe)2(μ-S)(CO)2] (14). Further heating of 14 in dichloromethane led to the formation of the chloromethanethiolate derivative [Mo2Cp2(μ-SMe)2(μ-SCH2Cl)(CO)2]Cl (15). Treatment of the bis(nitrile) species [Mo2Cp2(μ-SMe)3(MeCN)2]BF4 (4) under reflux in tetrahydrofuran with NaSH afforded, in valuable yields, the thio-amidato derivative [Mo2Cp2(μ-SMe)3(μ-MeCSNH)] (18). All new complexes have been characterized by elemental analyses and spectroscopic methods, supplemented for 7−10, 11′, 14, and 15 by X-ray diffraction studies

Physical education and sport in schools: policies and pedagogy

This special issue of European Physical Education Review directs attention to the exploration of contemporary relationships between physical education (PE) and sport in schools from pedagogical perspectives. It reflects the dynamic policy landscape of PE and sport internationally and seeks to extend insights into the pedagogical issues, challenges and opportunities arising from contemporary policy contexts and amidst new curriculum developments in PE

Synthesis of CdSe Nanoplatelets without Short-Chain Ligands: Implication for Their Growth Mechanisms

International audienceWe present a novel route for the synthesis of zinc blende CdSe nanoplatelets (NPLs) that exclude the use of short-chain alkyl carboxylates. CdSe NPLs obtained without acetates are shown to be extremely asymmetric and rectangular. The effects of several experimental parameters such as the nature of cadmium carboxylates, selenium precursors, and precursor concentration ratios are studied. Our experiments, together with complementary small-/ wide-angle X-ray scattering results, show that the formation of NPLs is not related to soft templating. We discuss our findings in regard to several other formation mechanisms of NPLs, which have appeared recently in the literature, and propose that the steric hindrance caused by ligand packing exerts an influence on the growth and geometry of two-dimensional NPLs

Identifying short surface ligands on metal phosphide quantum dots

International audienceThe control and understanding of the chemical and physical properties of quantum dots (QDs) demands detailed surface characterization. However, probing the immediate interface between the inorganic core and the ligands is still a major challenge. Here we show that using cross-polarization magic angle spinning (MAS) NMR, unprecedented information can be obtained on the surface ligands of Cd3P2 and InP QDs. The resonances of fragments which are usually challenging to detect like methylene or methyl near the surface, can be observed with our approach. Moreover, ligands such as hydroxyl and ethoxide which have so far never been detected at the surface can be unambiguously identified. This NMR approach is versatile, applicable to any phosphides and highly sensitive since it remains effective for identifying quantities as low as a few percent of surface atoms