Interactive procedural simulation of paper tearing with sound

International audienceWe present a phenomenological model for the real-time simulation of paper tearing and sound. The model uses as input rotations of the hand along with the index and thumb of left and right hands to drive the position and orientation of two regions of a sheet of paper. The motion of the hands produces a cone shaped deformation of the paper and guides the formation and growth of the tear. We create a model for the direction of the tear based on empirical observation, and add detail to the tear with a directed noise model. Furthermore, we present a procedural sound synthesis method to produce tearing sounds during interaction. We show a variety of paper tearing examples and discuss applications and limitations

Simplified modeling of a PWR reactor pressure vessel lower head failure in the case of a severe accident

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Unlocking the Catalytic Hydrogenolysis of Chlorosilanes into Hydrosilanes with Superbases

The efficient synthesis of hydrosilanes by catalytic ydrogenolysis of chlorosilanes is described, using an Iridum (III) pincer catalyst. A careful selection of a nitrogen base (incl. sterically hindered guanidines and phosphazenes) can unlock the preparation of Me3SiH, Et3SiH and Me2SiHCl in high yield (up to 98%), directly from their corresponding chlorosilanes

Vers la synthèse de réducteurs renouvelables à base de silicium

International audienceFaciliter l’émergence d’une économie circulaire du carbone, dans laquelle des déchets tels que le CO2 ou les résidusde la biomasse sont des matières premières, nécessite l’utilisation de réducteurs efficaces et recyclables, capablesde convertir des liaisons C–O en liaisons C–H et C–C. À cette fin, de nouvelles méthodes de production de réducteurssilylés ont été explorées, permettant de s’affranchir de l’utilisation d’hydrures métalliques dont la production esttrès énergivore. Les formiates de silicium, obtenus à partir d’acide formique, sont une nouvelle classe de mimesd’hydrosilanes. Alternativement, la synthèse d’hydrosilanes vrais a pu être réalisée par hydrogénolyse catalytiquede chlorosilanes, en utilisant H2 comme source d’hydrure

Unlocking the Catalytic Hydrogenolysis of Chlorosilanes into Hydrosilanes with Superbases

The efficient synthesis of hydrosilanes by catalytic ydrogenolysis of chlorosilanes is described, using an Iridum (III) pincer catalyst. A careful selection of a nitrogen base (incl. sterically hindered guanidines and phosphazenes) can unlock the preparation of Me3SiH, Et3SiH and Me2SiHCl in high yield (up to 98%), directly from their corresponding chlorosilanes

Hydride-free Hydrogenation: Unraveling the Mechanism of Electrocatalytic Alkyne Semihydrogenation by Nickel-Bipyridine Complexes

Hydrogenation reactions of carbon-carbon unsaturated bonds are central in synthetic chemistry. Efficient catalysis of these reactions classically recourses to heterogeneous or homogeneous transition-metal species. Whether thermal or electrochemical, C–C multiple bond catalytic hydrogenation commonly involves metal hydrides as key intermediates. Here, we report that the electrocatalytic semihydrogenation of alkynes by molecular Ni complexes proceeds without the mediation of a hydride intermediate. Through a combined experimental and theoretical investigation, we disclose a mechanism that primarily involves a nickelacyclopropene resting state upon alkyne binding to a low-valent Ni(0) species. A following sequence of protonation and electron transfer steps via Ni(II) and Ni(I)-vinyl intermediates then leads to olefin release in an overall ECEC pattern as the most favored pathway. Our results also evidence that pathways involving hydride intermediates are strongly disfavored, which in turns promotes high semihydrogenation selectivity by avoiding competing hydrogen evolution. While bypassing catalytically competent hydrides, this type of mechanism still retains inner-metal-sphere characteristics with the formation of organometallic intermediates, often essential to control regio- or stereo-selectivity. We think that this approach to electrocatalytic reductions of unsaturated organic groups can open new paradigms for hydrogenation or hydroelementation reactions

The Role of (tBu^{tBu}POCOP)Ir(I) and iridium(III) pincer complexes in the catalytic hydrogenolysis of silyl triflates into hydrosilanes

International audienceHydrosilanes are convenient reductants for a large variety of organic substrates, but they are produced via energy-intensive processes. These limitations call for the development of general catalytic processes able to transform Si–O into Si–H bonds. We report here the catalytic hydrogenolysis of R$_3$SiOTf (R = Me, Et, and Ph) species in the presence of a base (e.g., NEt$_3$), by the hydride complexes [($^{tBu}$POCOP)IrH(X)] (X = H and OTf; ($^{tBu}$POCOP = [1,3-C$_6$H$_3$)(OPtBu)$_2$]). Syntheses and crystal structures of new iridium(I) and iridium(III) complexes are presented as well as their role in the R$_3$SiOTf to R$_3$SiH transformation. The mechanisms of these reactions have been examined by DFT studies, revealing that the active species involved in the reduction of the Si–OTf vs Si–Cl bond are different. The rate-determining transition state is a base-assisted splitting of H$_2$, forming an iridium(III) dihydride species

Catalytic hydrogenolysis of silyl triflates to hydrosilanes using iridium pincer complexes

International audienceHydrosilanes are convenient reductants for a large variety of organic oxygenated substratesand they have been successfully applied in the conversion ofbio-based materialsl and C0$_2$At present, hydrosilanes are produced via energy intensive processes and they generate,after use, silicon oxides wastes su ch as siloxanes, which are difficult to recycle. Theselimitations call for the development of catalytic pro cesses able to transform Si-O bonds insiloxanes and derivatives (silyl halides and triflates) into Si-H hydrides.Very recently, the groups of Shimada and Schneider reported for the first time thehydrogenolysis of sorne silyl halides and triflates with iridium(lII) catalysts andruthenium(II). Following these preliminary reports, we studied the catalytic hydrogenolysisof R$_3$SiOTf (R = Me, Et, Ph) species in the presence of a base, by the dihydride complex(POCOP)IrH$_2$ (See figure above). Syntheses and crystal structures of sorne isolated Ir(l) andIr(III) complexes will be presented as well as their role in the R$_3$SiOTf to R$_3$SiHtransformation.The new (POCOP)Ir$^I$(TBD) complex, which splits H$_2$ to (POCOP)Ir$^{III}$H$_2$ at a low pressure, isa pre-catalyst in the hydrogenolysis of Si-OTf linkages. It can be easily obtained from(POCOP)IrHCI, using the TBD guanidine. To the best of our knowledge, such spontaneousreductive elimination by a weak base of an iridium(lII) hydro-chloride species is novel.The kinetic and thermodynamic profiles of the reaction were examined by means ofspectroscopic and DFT studies. The mechanism reveals that rate detennining step is thehydride transfer from (POCOP)IrH$_2$ to the silyl triflate. The base (e.g. NEt$_3$) is required todrive the thermodynalnics of the reaction, by promoting the regeneration of iridium hydridesintennediates, in the presence of H$_2$

The Role of (tBuPOCOP)Ir(I) and iridium(III) Pincer Complexes in the Catalytic Hydrogenolysis of Silyl Triflates into Hydrosilanes

Hydrosilanes are convenient reductants for a large variety of organic substrates, but they are produced via energy-intensive processes. These limitations call for the development of general catalytic processes able to transform Si‒O into Si‒H bonds. We report here the catalytic hydrogenolysis of R3SiOTf (R = Me, Et, Ph) species in the presence of a base (e.g. NEt3), by the hydride complexes [(tBuPOCOP)IrH(X)] (X = H, OTf; (tBuPOCOP = [(1,3-C6H3)(OPtBu)2]). Syntheses and crystal structures of new iridium(I) and iridium(III) complexes are presented as well as their role in the R3SiOTf to R3SiH transformation. The mechanisms of these reactions have been examined by DFT studies, revealing that the rate-determining step is the base-assisted splitting of H

Metal‐Free Catalytic Hydrogenolysis of Chlorosilanes into Hydrosilanes with “Inverse” Frustrated Lewis Pairs

International audienceThe challenging metal‐free catalytic hydrogenolysis of silyl chlorides to hydrosilanes is unlocked by using an inverse frustrated Lewis pair (FLP), combining a mild Lewis acid (Cy 2 BCl) and a strong phosphazene base (BTPP) in mild conditions (10 bar of H 2 , r. t.). In the presence of a stoichiometric amount of the base, the hydrosilanes R 3 SiH (R=Me, Et, Ph) are generated in moderate to high yields (up to 95 %) from their chlorinated counterparts. A selective formation of the valuable difunctional monohydride Me 2 SiHCl is also obtained from Me 2 SiCl 2 . A mechanism is proposed based on stoichiometric experiments and DFT calculations; it highlights the critical role of borohydride species generated by the heterolytic splitting of H 2