Publications by authors named "Nicolas Mezailles"

Reactivity of (triphosphine)Mo-nitrido complex generated by N splitting, toward boranes is reported. The simple adduct Mo≡N→BH is observed with BH.SMe while 1,2 addition is evidenced with 9-BBN leading to H-Mo=NBR.

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Numerous synthetic models of the FeMo-co cluster of nitrogenases have been proposed to find the simplest structure with relevant reactivity. Indeed, such structures are able to perform multi-electrons reduction processes, such as the conversion of N to ammonia, and of CO into methane and alkenes. The most challenging parameter to imitate is indeed the central carbide ligand, which is believed to maintain the integrity of iron sulfide assembly during the course of catalytic cycles.

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A DFT study of several L→Al(OR ) (L=Lewis bases) adducts allowed the identification of ( Pr S)→Al(OR ) 1-S Pr as a "stable yet reactive" adduct. 1-S Pr was shown to act as a masked Lewis superacid able to release Al(OR ) under mild conditions. It could be used to abstract a OR ligand from (bipyMe )Ni(OR ) (bipyMe  : 6,6'-dimethyl-2,2'-dipyridyl) and generate the nickel alkoxide complex [(bipyMe )Ni(OR )( Pr S)] [(R O) Al-F-Al(OR ) ] 5.

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Two different dinitrogen-derived molybdenum nitrido complexes varying by their geometry, ligand spheres and oxidations states were shown to engage their N ligand in dative bonding with the strong Lewis acid B(C F ) . The stable adducts were assessed for frustrated Lewis pair-type heterolytic E-H bond splitting of hydrosilanes (E=Si) and HB(C F ) . Whereas Si-H bond activation was achieved, HB(C F ) was shown to substitute B(C F ) in a quantitative or equilibrated fashion, depending on the nature of the nitrido complex.

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Ammonia, NH , is an essential molecule, being part of fertilizers. It is currently synthesized via the Haber-Bosch process, from the very stable dinitrogen molecule, N and dihydrogen, H . This process requires high temperatures and pressures, thereby generating ca 1.

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Nitrogen reduction under mild conditions (room T and atmospheric P), using a non-fossil source of hydrogen remains a challenge. Molecular metal complexes, notably Mo based, have recently been shown to be active for such nitrogen fixation. We report electrochemical N splitting with a Mo triphosphino complex [(PPP)MoI ], at room temperature and a moderately negative potential.

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In ample variety of transformations, the presence of silver as an additive or co-catalyst is believed to be innocuous for the efficiency of the operating metal catalyst. Even though Ag additives are required often as coupling partners, oxidants or halide scavengers, its role as a catalytically competent species is widely neglected in cross-coupling reactions. Most likely, this is due to the erroneously assumed incapacity of Ag to undergo 2e redox steps.

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Catalytic formation of borylamines from atmospheric N is achieved for the first time using a series of homogenous (triphosphine)Mo complexes. Stepwise functionalization of the (triphosphine)Mo-nitrido complex with chloroborane led to the synthesis of the imido complex. Electrochemical characterization of the (PPP)Mo-nitrido and (PPP)Mo-borylimido complexes showed that the latter is much more easily reduced.

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Reduction of high spin paramagnetic complex [(κ2-P, P'-PCH2PCy)FeCl2] 2 by two electrons under N2 resulted in the formation of two isomeric low spin diamagnetic complexes 3trans and 3cis [Fe(κ3-P,C,P'-PCPCy)(H)2(N2)]. Cristallization allowed isolation of complex 3d [Fe(κ3-P,C,P'-PCPCy)(H)2]2(μ-N2), characterized by X-ray diffraction, Mössbauer and Raman spectroscopies. DFT calculations rationalized the facile double α,α CH bond insertion into a single sp3 CH2 moiety, as well as the fast exchange positions of the hydrides in the cis dihydride complex observed by NMR spectrocscopy.

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This study describes the first use of a bis(phosphoranyl)methanido aluminum hydride, [ClC(PPhNMes)AlH] (, Mes = MeCH), for the catalytic hydroboration of CO. Complex was synthesized by the reaction of a lithium carbenoid [Li(Cl)C(PPhNMes)] with 2 equiv of AlH·NEtMe in toluene at -78 °C. (10 mol %) was able to catalyze the reduction of CO with HBpin in CD at 110 °C for 2 days to afford a mixture of methoxyborane [MeOBpin] (; yield: 78%, TOF: 0.

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The direct synthesis of nitrile from N under mild conditions is of great importance and has attracted much interest. Herein, we report a direct conversion of N into nitrile via a nitrile-alkyne cross-metathesis (NACM) process involving a N -derived Mo nitride. Treatment of the Mo nitride with alkyne in the presence of KOTf afforded an alkyne-coordinated nitride, which was then transformed into Mo carbyne and the corresponding nitrile upon 1 e oxidation.

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The role of indium carboxylate precursors in the synthesis of monodisperse InP quantum dots was investigated. The reaction between acid-free indium palmitate and tris(trimethylsilyl)phosphine (P(TMS)) was monitored by using high-temperature P NMR, indicating the presence of a single molecular phosphorus species throughout the duration of the reaction. The addition of varying amounts of carboxylic acid and its effects on both the reaction kinetics and the optical properties of InP QDs were studied.

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The [4+2] cycloaddition of 2-(2'-pyridyl)-4,6-diphenyl-λ -phosphinine with the highly reactive dienophile hexafluoro-2-butyne has been studied and the first pyridyl-functionalized 1-phosphabarrelene was obtained and structurally characterized. Although monodentate CF -1-phosphabarrelenes show only a poor coordination ability, the chelating nature of the novel P,N-hybrid ligand gives access to various transition-metal complexes. Upon irradiation with UV light, the pyridyl-functionalized 1-phosphabarrelene undergoes a rather selective di-π-methane rearrangement in the coordination sphere of the metal center, leading to the formation of a complex based on a hitherto unknown pyridyl-functionalized 5-phosphasemibullvalene derivative.

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This review is dedicated to the chemistry of stable and isolable species that bear two lone pairs at the same C center, i.e., geminal dianions, stabilized by main group elements.

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A series of substituted phosphinines, 1-phosphabarrelenes and 5-phosphasemibullvalenes were synthesized and evaluated for their potential application as ligands in homogeneous catalytic reactions. While their buried volume (%V ) was calculated to get insight into the steric properties, [LNi(CO) ] complexes were prepared in order to determine the corresponding Tolman electronic parameter. ETS-NOCV (extended-transition-state natural orbital for chemical valence) calculations on [LAuCl] complexes further allowed an estimation of the σ- and π-contributions to the L-M interaction.

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The reduction of [Ni(DME)Cl2] with 2 equiv. of bis(trimethylsilyl)-1,4-tetramethyldihydropyrazine in the presence of a ligand L and an excess of olefin cleanly leads to [Ni(L)(alkene)2] complexes. When reduction is performed in the presence of 1,5-cyclooctadiene (COD), [Ni(COD)2] is obtained.

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The two electron reduction of iron complexes [(PP)Fe(Cl)] (R = Ph or tBu) 2a-b afforded complexes [(PP)Fe(N)] 4a-b. Protonation of 4a at the metal center and subsequent reduction to Fe(i)-H species lead to complex [(PP)Fe(N)(H)] 6avia a spontaneous disproportionation reaction. Complex 4a behaves as one of the most efficient monometallic Fe-catalysts reported to date for N-to-N(SiMe) functionalization under atmospheric pressure.

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Intermolecular, stepwise functionalization by BH bonds of a (triphosphine)Mo -nitrido complex generated by N splitting is reported. The imido-hydride and di-hydride-amido Mo complexes have been isolated and characterized. Addition of PinBH to the [Mo(H) (N(BPin) )] complex at room temperature results in the liberation of borylamines from the metal center.

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Reduction of the Fe complex [( PP )FeCl ] (2) generated an electron-rich and unsaturated Fe species, which was reacted with white phosphorus. The resulting new complex, [( PP )Fe(η -P )] (3), is the first iron cyclo-P complex and the only known stable end-deck cyclo-P complex outside Group V. Complex 3 features an Fe center, as shown by Mössbauer spectroscopy, associated to a P fragment.

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The robust, high-valent Ni complex [(Py) Ni F (CF ) ] (Py=pyridine) was synthesized and fully characterized by NMR spectroscopy, X-ray diffraction, and elemental analysis. It reacts with aromatic compounds at 25 °C to form the corresponding benzotrifluorides in nearly quantitative yield. The monomeric and dimeric Ni CF complexes 2⋅Py and 2 were identified as key intermediates, and their structures were unambiguously determined by EPR spectroscopy and X-ray diffraction.

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The first Au carbene complex was prepared by reacting a geminal dianion with a (P,C) cyclometalated Au precursor. Its structure and bonding situation have been thoroughly investigated by experimental and computational means. The presence of a high-energy highest occupied molecular orbital (HOMO) centered at the carbene center suggests nucleophilic character for the Au carbene complex.

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Herein, we present a detailed study of the conversion of a nickel(II) diamide precursor to size-tunable, monodisperse nickel nanoparticles (NPs). The thermal decomposition of nickel(II) dioleylamide, synthesized either independently or in situ, resulted in the formation of Ni NPs without the coproduction of water. Mechanistic studies were conducted on the stability and reduction pathway of the Ni precursor, and on the consequent particle formation.

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We report the water-assisted synthesis of indium nanoparticles (In NPs). We found that a precise amount of water was necessary to allow the formation of the desired 7 nm In NPs: the oxidation of the In surface by water inhibits the growth of NPs as well as subsequent reactivity with white phosphorus (P). A novel surface activation method based on the use of organosilanes is presented.

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A homogeneous system which is able to yield silylamine from N2 and bis(silane) in one pot is reported. Mechanistically a {(triphosphine)molybdenum(I)} fragment, generated in situ, splits N2 into the corresponding nitrido complex at room temperature. Then, functionalization of the molybdenum nitrido is achieved by double Si-H addition under mild reaction conditions.

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A direct method for white phosphorus functionalization by hydride sources is presented. Excess BH4(-) in n-butylamine produces HP4(-) as the major P-containing species. Reaction with LiBEt3H forms the borane-stabilized phosphanide Li(PH2)(BEt3)2, which may be used to synthesize various phosphines.

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