Search

Reactivity of (triphosphine)Mo IV -nitrido complex generated by N 2 splitting, toward boranes is reported. The simple adduct Mo≡N→BH 3 is observed with BH 3 .SMe 2 while 1,2 addition is evidenced with 9-BBN leading to H-Mo=NBR 2 . A second addition of BH 3 .SMe 2 is facile and forms an unprecedented complex featuring two bridging H between two B and the Mo centers. Addition of PMe 3 or BH 3 .SMe 2 promotes reductive elimination and N-H bond formation. The full sequence of functionalization at Mo≡N obtained after N 2 splitting is therefore evidenced in this work., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

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 2 to ammonia, and of CO 2 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. The study proposes the use of bis(diphenylthiophosphinoyl)methanediide (SCS) 2- as an ideal platform for the synthesis of bi- and tetra-metallic iron complexes, in which the iron-carbon interaction is maintained upon structural diversification and redox state changes., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

A DFT study of several L→Al(OR F ) 3 (L=Lewis bases) adducts allowed the identification of ( i Pr 2 S)→Al(OR F ) 3 1-S i Pr 2 as a "stable yet reactive" adduct. 1-S i Pr 2 was shown to act as a masked Lewis superacid able to release Al(OR F ) 3 under mild conditions. It could be used to abstract a OR F- ligand from (bipyMe 2 )Ni(OR F ) 2 (bipyMe 2  : 6,6'-dimethyl-2,2'-dipyridyl) and generate the nickel alkoxide complex [(bipyMe 2 )Ni(OR F )( i Pr 2 S)] + [(R F O) 3 Al-F-Al(OR F ) 3 ] - 5. Ligand exchange of i Pr 2 S by Ph 3 P yielded [(bipyMe 2 )Ni(OR F )(PPh 3 )] + [(R F O) 3 Al-F-Al(OR F ) 3 ] - 6., (© 2023 Wiley-VCH GmbH.)

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 6 F 5 ) 3 . The stable adducts were assessed for frustrated Lewis pair-type heterolytic E-H bond splitting of hydrosilanes (E=Si) and HB(C 6 F 5 ) 2 . Whereas Si-H bond activation was achieved, HB(C 6 F 5 ) 2 was shown to substitute B(C 6 F 5 ) 3 in a quantitative or equilibrated fashion, depending on the nature of the nitrido complex. No B-H bond splitting was observed. Thermodynamics of these reactions, computed by DFT, are in agreement with the experimental outcomes., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Ammonia, NH 3 , is an essential molecule, being part of fertilizers. It is currently synthesized via the Haber-Bosch process, from the very stable dinitrogen molecule, N 2 and dihydrogen, H 2 . This process requires high temperatures and pressures, thereby generating ca 1.6 % of the global CO 2 emissions. Alternative strategies are needed to realize the functionalization of N 2 to NH 3 under mild conditions. Here, we show that boron-centered radicals provide a means of activating N 2 at room temperature and atmospheric pressure whilst allowing a radical process to occur, leading to the production of borylamines. Subsequent hydrolysis released NH 4 + , the acidic form of NH 3 . EPR spectroscopy supported the intermediacy of radicals in the process, corroborated by DFT calculations, which rationalized the mechanism of the N 2 functionalization by R 2 B radicals., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

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 2 splitting with a Mo III triphosphino complex [(PPP)MoI 3 ], at room temperature and a moderately negative potential. A Mo IV nitride species was generated, which is confirmed by electrochemistry and NMR studies. The reaction goes through two successive one electron reductions of the starting Mo species, coordination of a N 2 molecule, and further splitting to a Mo IV nitride complex. Preliminary DFT studies support the formation of a bridging Mo I N 2 Mo I dinitrogen dimer evolving to the Mo nitride via a low energy transition state. This example joins a short list of molecular complexes for N 2 electrochemical reductive cleavage. It opens a door to electrochemical proton-coupled electron transfer (PCET) conversion studies of N 2 to NH 3 ., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

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. Definite proof is herein provided for the required elementary steps to accomplish the oxidative trifluoromethylation of arenes through Ag I /Ag III redox catalysis (i. e. CEL coupling), namely: i) easy Ag I /Ag III 2e - oxidation mediated by air; ii) bpy/phen ligation to Ag III ; iii) boron-to-Ag III aryl transfer; and iv) ulterior reductive elimination of benzotrifluorides from an [aryl-Ag III -CF 3 ] fragment. More precisely, an ultimate entry and full characterization of organosilver(III) compounds [K] + [Ag III (CF 3 ) 4 ] - (K-1), [(bpy)Ag III (CF 3 ) 3 ] (2) and [(phen)Ag III (CF 3 ) 3 ] (3), is described. The utility of 3 in cross-coupling has been showcased unambiguously, and a large variety of arylboron compounds was trifluoromethylated via [Ag III (aryl)(CF 3 ) 3 ] - intermediates. This work breaks with old stereotypes and misconceptions regarding the inability of Ag to undergo cross-coupling by itself., (© 2021 Wiley-VCH GmbH.)

Catalytic formation of borylamines from atmospheric N 2 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., (© 2021 Wiley-VCH GmbH.)

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.

The direct synthesis of nitrile from N 2 under mild conditions is of great importance and has attracted much interest. Herein, we report a direct conversion of N 2 into nitrile via a nitrile-alkyne cross-metathesis (NACM) process involving a N 2 -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 V carbyne and the corresponding nitrile upon 1 e - oxidation. Both aryl- and alkyl-substituted alkynes underwent this process smoothly. Experiments and DFT calculations have proved that the oxidation state of the Mo center plays a crucial role. This method does not rely on the nucleophilicity of the N 2 -derived metal nitride, offering a novel strategy for N 2 fixation chemistry., (© 2021 Wiley-VCH GmbH.)

This study describes the first use of a bis(phosphoranyl)methanido aluminum hydride, [ClC(PPh 2 NMes) 2 AlH 2 ] ( 2 , Mes = Me 3 C 6 H 2 ), for the catalytic hydroboration of CO 2 . Complex 2 was synthesized by the reaction of a lithium carbenoid [Li(Cl)C(PPh 2 NMes) 2 ] with 2 equiv of AlH 3 ·NEtMe 2 in toluene at -78 °C. 2 (10 mol %) was able to catalyze the reduction of CO 2 with HBpin in C 6 D 6 at 110 °C for 2 days to afford a mixture of methoxyborane [MeOBpin] ( 3a ; yield: 78%, TOF: 0.16 h -1 ) and bis(boryl)oxide [pinBOBpin] ( 3b ). When more potent [BH 3 ·SMe 2 ] was used instead of HBpin, the catalytic reaction was extremely pure, resulting in the formation of trimethyl borate [B(OMe) 3 ] ( 3e ) [catalytic loading: 1 mol % (10 mol %); reaction time: 60 min (5 min); yield: 97.6% (>99%); TOF: 292.8 h -1 (356.4 h -1 )] and B 2 O 3 ( 3f ). Mechanistic studies show that the Al-H bond in complex 2 activated CO 2 to form [ClC(PPh 2 NMes) 2 Al(H){OC(O)H}] ( 4 ), which was subsequently reacted with BH 3 ·SMe 2 to form 3e and 3f , along with the regeneration of complex 2 . Complex 2 also shows good catalytic activity toward the hydroboration of carbonyl, nitrile, and alkyne derivatives.

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) 3 ) was monitored by using high-temperature 31 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. In the presence of acid, rapid protonation of P(TMS) 3 led to the formation of a mixture of four H x P(TMS) 3- x species, resulting in the poorer controlled formation of InP nanocrystals. Upon deposition of a gradated ZnSeS shell on the synthesized InP core, luminescent quantum dots were obtained (QY 67%; PL: FWHM 40 nm).

The [4+2] cycloaddition of 2-(2'-pyridyl)-4,6-diphenyl-λ 3 -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 3 -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. DFT calculations provide first insights into the mechanism of this reaction., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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. Three cases can thus be considered: the geminal -dilithio derivative, for which the two substituents at C are neutral, the yldiide derivatives, for which one substituent is neutral while the other is charged, and finally the geminal bisylides, for which the two substituents are positively charged. In this review, the syntheses and electronic structures of the geminal dianions are presented, followed by the studies dedicated to their reactivity toward organic substrates and finally to their coordination chemistry and applications.

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 bur ) was calculated to get insight into the steric properties, [LNi(CO) 3 ] 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. Au I coordination compounds of selected examples were prepared and characterized by single crystal X-ray diffraction. Finally, the three classes of P III compounds were successfully used in the Au I -catalyzed cycloisomerization of N-2-propyn-1-ylbenzamide, showing very good activities and selectivities, which are comparable with the reported data of cationic phosphorus-based gold catalysts., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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. Such an approach also allows access to the NiI dimer [Ni(bis(dicyclohexylphosphino)propane)Cl]2.

The two electron reduction of iron complexes [(P R P 2 Cy )Fe(Cl) 2 ] (R = Ph or tBu) 2a-b afforded complexes [(P R P 2 Cy )Fe(N 2 ) 2 ] 4a-b. Protonation of 4a at the metal center and subsequent reduction to Fe(i)-H species lead to complex [(P Ph P 2 Cy )Fe(N 2 )(H) 2 ] 6avia a spontaneous disproportionation reaction. Complex 4a behaves as one of the most efficient monometallic Fe-catalysts reported to date for N 2 -to-N(SiMe 3 ) 3 functionalization under atmospheric pressure.

Intermolecular, stepwise functionalization by BH bonds of a (triphosphine)Mo IV -nitrido complex generated by N 2 splitting is reported. The imido-hydride and di-hydride-amido Mo IV complexes have been isolated and characterized. Addition of PinBH to the [Mo(H) 2 (N(BPin) 2 )] + complex at room temperature results in the liberation of borylamines from the metal center., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Reduction of the Fe II complex [( Ph PP 2 Cy )FeCl 2 ] (2) generated an electron-rich and unsaturated Fe 0 species, which was reacted with white phosphorus. The resulting new complex, [( Ph PP 2 Cy )Fe(η 4 -P 4 )] (3), is the first iron cyclo-P 4 complex and the only known stable end-deck cyclo-P 4 complex outside Group V. Complex 3 features an Fe II center, as shown by Mössbauer spectroscopy, associated to a P 4 2- fragment. The distinct reactivity of complex 3 was rationalized by analysis of the molecular orbitals. Reaction of complex 3 with H + afforded the unstable complex [( Ph PP 2 Cy )Fe(η 4 -P 4 )(H)] + (4), whereas with CuCl and BCF, the complexes [( Ph PP 2 Cy )Fe(η 4 :η 1 -P 4 )(μ-CuCl)] 2 (5) and [( Ph PP 2 Cy )Fe(η 4 :η 1 -P 4 )B(C 6 F 5 ) 3 ] (6) were formed., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The robust, high-valent Ni IV complex [(Py) 2 Ni IV F 2 (CF 3 ) 2 ] (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 III CF 3 complexes 2⋅Py and 2 were identified as key intermediates, and their structures were unambiguously determined by EPR spectroscopy and X-ray diffraction. Preliminary kinetic studies in combination with the isolation of reaction intermediates confirmed that the C-H bond-breaking/C-CF 3 bond-forming sequence can occur both at Ni IV CF 3 and Ni III CF 3 centers., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The first Au III carbene complex was prepared by reacting a geminal dianion with a (P,C) cyclometalated Au III 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 III carbene complex. This unprecedented feature was confirmed by reactions with two electrophiles (PhNCS and CS 2 ), resulting in two types of C=C coupling reactions., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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 II precursor, and on the consequent particle formation. Variations in the ratio of trioctylphosine (TOP) to nickel allowed size tunability, which resulted in nanoparticles that ranged in size from 4 to 11 nm in diameter. The DFT calculations support a mechanistic pathway that involves nickel reduction by imine formation. This water-free method was extended to the synthesis of water-sensitive M 0 NPs (M=Fe, Co)., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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 4 ). A novel surface activation method based on the use of organosilanes is presented.

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. Moreover, the bis(silyl)amine product is decoordinated from the metal center., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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. Triethylborane may be replaced by BH3, resulting in the formation of LiPH2(BH3)2.

Research on nanomaterials and nanostructured materials is burgeoning because their numerous and versatile applications contribute to solve societal needs in the domain of medicine, energy, environment and STICs. Optimizing their properties requires in-depth analysis of their structural, morphological and chemical features at the nanoscale. In a transmission electron microscope (TEM), combining tomography with electron energy loss spectroscopy and high-magnification imaging in high-angle annular dark-field mode provides access to all features of the same object. Today, TEM experiments in three dimensions are paramount to solve tough structural problems associated with nanoscale matter. This approach allowed a thorough morphological description of silica fibers. Moreover, quantitative analysis of the mesoporous network of binary metal oxide prepared by template-assisted spray-drying was performed, and the homogeneity of amino functionalized metal-organic frameworks was assessed. Besides, the morphology and internal structure of metal phosphide nanoparticles was deciphered, providing a milestone for understanding phase segregation at the nanoscale. By extrapolating to larger classes of materials, from soft matter to hard metals and/or ceramics, this approach allows probing small volumes and uncovering materials characteristics and properties at two or three dimensions. Altogether, this feature article aims at providing (nano)materials scientists with a representative set of examples that illustrates the capabilities of modern TEM and tomography, which can be transposed to their own research.

The use of a strongly donating "(bis-dialkylphosphine)Ni" fragment promotes the catalytic coupling of a large range of ArCl and ArZnCl derivatives under mild conditions. Stoichiometric mechanistic investigations and DFT calculations prove that a Ni(0) /Ni(II) cycle is operative in this system., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The treatment of Li2C(PPh2NMes)2 (1, Mes = 2,4,6-Me3C6H2) with hexachloroethane yielded the corresponding carbenoid 2 in good yields. The reactivity of 2 was studied with BH3·SMe2 to give a zwitterionic boronium species 4, also a stable carbenoid. Both carbenoid species were found to be excellent catalysts for the CO2 reduction by BH3·SMe2.

The synthesis of two novel titanium carbene complexes from the bis(thiophosphinoyl)methanediide geminal dianion 1 (SCS(2-) ) is described. Dianion 1 reacts cleanly with 0.5 equivalents of [TiCl4 (thf)2 ] to afford the bis-carbene complex [(SCS)2 Ti] (2) in 86 % yield. The mono-carbene complex [(SCS)TiCl2 (thf)] (3) can also be obtained by using an excess of [TiCl4 (thf)2 ]. The structures of 2 and 3 are confirmed by X-ray crystallography. A strong nucleophilic reactivity towards various electrophiles (ketones and aldehydes) is observed. The reaction of 3 with N,N'-dicyclohexylcarbodiimide (DCC) and phenyl isocyanate leads to the formation of two novel diphosphinoketenimines 8 a and 8 b. The bis-titanium guanidinate complex 9 is trapped as the by-product of the reaction with DCC. The X-ray crystal structures of 8 a and 9 are presented. The mechanism of the reaction between complex 3 and DCC is rationalized by DFT studies., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Stoichiometric reduction of N2 at a Mo center stabilized by a bulky tetradentate phosphine ligand (PP3(Cy)) allowed isolation of Mo-imidoamine and Mo-imido complexes. Both complexes as well as the Mo(II) precursor are equally suitable catalysts for the synthesis of NTMS3 (TMS = trimethylsilyl) from N2, TMSCl, and electron sources. Mechanistic studies prove the involvement of a TMS radical at least in one of the catalytic steps., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The notions of nanoscale "phase speciation" and "phase diagram" are defined and discussed in terms of kinetic and thermodynamic controls, based on the case of metal phosphide nanoparticles. After an overview of the most successful synthetic routes for these exotic nanomaterials, the cases of InP, Ni2 P, Ni12 P5 and Pdx Py are discussed in detail to highlight the relationship between composition, structure, and size at the nanoscale. The influence of morphology is discussed next by comparing the behavior of Cu3 P nanophases with those of Nix Py , FeP/Fe2 P, and CoP/Co2 P. Perspectives provide the reader with methodological guidelines for further investigation of nanoscale "phase diagrams", and their use for optimized synthesis of new functional nanomaterials., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Stable nucleophilic carbene compounds have recently been shown to be able to mimic in some instances the reactivity of metal fragments in the reaction of unactivated E-H bonds (E = H, R3Si, NH2, R2P). However, the insertion into a B-H bond of the strongly Lewis acidic BH3 molecule has never been observed at a single C atom or even at a metal fragment. Our results show that designed stable, highly electrophilic carbenoid fragments in compounds 4 and 6 can achieve this reactivity in a controlled manner. Density functional theory calculations corroborated the experimental results on the presently designed systems as well as the lack of reactivity on nucleophilic carbenes.

A new unsymmetrical geminal dianion that contained both a phosphine oxide moiety and a phosphine sulfide moiety has been synthesized. Its reactivity towards Ru(II) was explored, which led to the formation of a highly reactive carbene complex that evolved at room temperature to yield a kinetic orthometalated Ru(II) complex through C-H activation of the phenyl group of the phosphine oxide moiety. This insertion was found to be thermally reversible and a second C-H insertion occurred at a phenyl group of the phosphine sulfide moiety to form the thermodynamic orthometalated Ru(II) complex in a diastereospecific manner. DFT calculations fully rationalized the experimental findings in terms of the relative energies of the kinetic and thermodynamic products and allowed the mechanism of this process to be fully understood., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The widely used preparation of Ni(0) nanoparticles from [Ni(acac)(2)] (acac=acetylacetonate) and oleylamine, often considered to be a thermolysis or a radical reaction, was analyzed anew by using a combination of DFT modeling and designed mechanistic experiments. Firstly, the reaction was followed up by using TGA to evaluate the energy barrier of the limiting step. Secondly, all the byproducts were identified using NMR spectroscopy, mass spectrometry, FTIR, and X-ray crystallography. These methods allowed us to depict both main and side-reaction pathways. Lastly, DFT modeling was utilized to assess the validity of this new scheme by identifying the limiting steps and evaluating the corresponding energy barriers. The oleylamine was shown to reduce the [Ni(acac)(2)] complex not through a one-electron radical mechanism, as often stated, but as an hydride donor through a two-electron chemical reduction route. This finding has strong consequences not only for the design of further nanoparticles syntheses that use long-chain amine as a reactant, but also for advanced understanding of catalytic reactions for which these nanoparticles can be employed., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Room temperature reversible C-H activation mediated by a designed diphosphine platinum complex is presented. These findings are demonstrated through mechanistic studies involving kinetics, isotopic effects, and corroborated by DFT calculations. The coupling between two unactivated aromatic derivatives is also demonstrated.

Early transition metal nucleophilic carbene complexes have been used as stoichiometric carbene transfer agents in a transmetalation process.

An air-stable, bulky electron-accepting phosphine ligand (phosphabarrelene) allows the easy reduction of a Pd(II) precursor to a Pd(0) complex, highly active in room-temperature Negishi-type cross-coupling. DFT calculations show that the use of the electron-accepting ligand favors both transmetalation (TM) and reductive-elimination (RE) processes (see scheme; OA = oxidative addition)., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Uranyl organometallic complexes featuring uranium(VI)-carbon single and double bonds have been obtained from uranyl UO(2)X(2) precursors by avoiding reduction of the metal center. X-ray diffraction and density functional theory analyses of these complexes showed that the U-C and U=C bonds are polarized toward the nucleophilic carbon.

The catalytic activity both of cationic [(XDPP)Au][X] (XDPP = bis-2,5-diphenylphosphole xantphos X = BF(4)) and of the isolated gold hydride complex [(XDPP)(2)Au(2)H][OTf] in the dehydrogenative silylation process is presented. A parallel theoretical study using density functional theory revealed a mechanism involving the counter anion as a co-catalyst, which was experimentally confirmed by testing various counterions (X = OTf, NTf(2), PF(6)). Finally, a "Au(2)H(+)" species was determined as the intermediate during the catalytic cycle, which correlates well with the experimental findings on the first example of catalytic activity of an isolated "Au-H" complex., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Enantiopure undecagold clusters protected by chiral atropisomeric diphosphine ligands (P^P) have been synthesized by the stoichiometric reduction of the corresponding (P^P)(AuCl)(2) complexes with NaBH(4). The molecular mono-disperse [Au(11)(P^P)(4)Cl(2)]Cl species have been thoroughly characterized using an array of analytical techniques. (31)P NMR experiments suggested the presence of a slow intramolecular ligand exchange process. Circular dichroism measurements showed that enantiomeric clusters display mirror-image chiroptical activity. Such undecagold clusters containing two chloride ligands bound to the peripheral Au(I) atoms were expected to display a carbophilic Lewis acidity similar to the well-documented molecular Au(I) complex catalysts. Chloride abstraction, performed to generate active Au(+) sites, induced the Au(11) cluster evolution to larger gold clusters and nanoparticles, together with Au(I) complexes, which, in fact, perform the catalysis. This result was corroborated by running an asymmetric tandem hydroarylation-carbocyclization reaction, for which the enantiomeric excesses obtained with Au(11) clusters are similar to those reported using Au(I) complexes.

Using a geminal dianion as precursor, a nucleophilic scandium carbene complex (2) has been synthesized by salt metathesis on ScCl(3)(THF)(3) in 52% isolated yield. The X-ray structure as well as an NBO analysis points to a double interaction between the carbon and the scandium atoms. Quantification of the electron density donation from the carbon to the metal center, from both σ and π symmetry orbitals, predicts a "nucleophilic carbene" behavior. Addition of benzophenone on complex 2 results in the formation of the expected alkene derivative and the trapping of a rare, μ(3)-oxo-Sc species via a "scandia-Wittig" reaction.

P(4) reaction with metal NPs (In, Pb, Zn) provides an easy access to the corresponding metal phosphide NPs in a soft and stoichiometric reaction. Size-influence on the reactivity is investigated in the case of indium.

Metathesis reactions of UCl(4) with Li(2)C(Ph(2)PS)(2) in Et(2)O only afforded the tris-carbene complex [{Li(OEt(2))}(2)U{=C(Ph(2)PS)(2)}(3)] (1), while the bis- and mono-carbene compounds [U{=C(Ph(2)PS)(2)}(2)(THF)(2)] (2) and [{Li(THF)(2)}(2)U{=C(Ph(2)PS)(2)}Cl(4)] (3) were obtained by treatment of UCl(4) with Li(2)C(Ph(2)PS)(2) in a mixture of THF and toluene. The bis-carbene complex 2 was also obtained either from the comproportionation reaction of 1 and UCl(4) or protonolysis reaction of U(NEt(2))(4) with H(2)C(Ph(2)PS)(2) and was transformed into the mono-carbene complex [U{=C(Ph(2)PS)(2)}Cl(2)(THF)(2)] (4) by further reaction with UCl(4). The utility of these complexes as precursors is illustrated by the synthesis of the biscyclopentadienyl derivative [Cp(2)U{=C(Ph(2)PS)(2)}] (5) by treatment of 3 with TlCp. The crystal structures of [U{=C(Ph(2)PS)(2)}(2)(py)(2)].1.5py.0.5THF and 5.toluene are reported.

The reactivity of the geminal dianion of tetraisopropyl methylenediphosphonate, 3, with [ZrCl4(THF)2] affords a trinuclear structure 5 in which an unprecedented triscarbene-Zr dianionic fragment is found. The overall trinuclear arrangement is assembled by PO bridging moieties. The X-ray crystal structure of 5 is presented. The reaction of complex 5 with stoichiometric amounts of pyridine affords a dinuclear complex 6 whose formulation was ascertained by an X-ray crystal structure. Complexes 5 and 6 cleanly react with aldehydes (R1)(H)CO to afford the corresponding olefin of general formula [((OiPr)2P=O)2C=C(R1)(H)]. DFT calculations which were carried out on the model complex of 5t and a hypothetical monometallic Zr complex [Zr(3)Cl2(OMe2)2] 8t indicate that the Zr-C bond only features a weak pi-interaction between the carbon atom and a vacant orbital at the metal. The polarization of the orbital towards the carbon center is consistent with the observed nucleophilic character of the carbene complexes described here.

The bis-2,5-diphenylphosphole xantphos ligand (XDPP) 1 reacts with the [AuCl(tht)] complex to afford the monocoordinated [Au(XDPP)Cl] 2 and the dicoordinated chelate species [Au(XDPP)Cl] 3. Addition of AgOTf on this mixture, at room temperature, affords the cationic [Au(XDPP)][OTf] complex 4 which was fully characterized. An X-ray crystal structure analysis confirms the bent structure of this 14 VE [ML(2)](+) complex. Reaction of 4 with HSiMe(2)Ph in tetrahydrofuran at -78 degrees C yields the dinuclear [(XDPP)Au-H-Au(XDPP)](+) cationic complex 5, in which the hydride bridges the two [Au(XDPP)](+) metal fragments. In 5, the Au-P bond lengths are different and the phosphorus atoms which are located nearly trans to the hydride ligand exhibit significantly shorter P-Au bond lengths. Reaction of 4 with DSiMe(2)Ph to form the [(XDPP)Au-D-Au(XDPP)](+) complex 6 allowed to unambiguously ascribe the chemical shift of the deuteride in (2)H NMR (delta = 7.0 ppm with a (2)J(DP) = 8.4 Hz. The electronic structure of the [(XDPP)Au-H-Au(XDPP)](+) complex was studied through density functional theory calculations. An orbital analysis is developed in which complex 5 is viewed as the combination of two 12 electrons fragments [Au(XDPP)](+) with H(-). This analysis reveals that the hydride interacts in a bonding way with the sigma MO between the two gold atoms and in an antibonding way with a combination of d orbitals at the metal centers. This simple description allows to rationalize the inequivalence of the two types of P-Au bonds in 5.

The stoichiometric reaction of [Rh(COD)Cl](2) with the anion resulting from the deprotonation of dppm(BH(3))(2) yielded a new alkyl Rh(I) complex; the coordination modes of the BH(3) groups are discussed on the basis of X-ray data, variable temperature multinuclear NMR experiments and DFT studies.

Treatment of U(BH(4))(4) with 1 or 3 equiv of Li(2)(SCS) x 1.5 Et(2)O, 1, afforded the actinide carbene complexes U(mu-SCS)(3)[U(BH(4))(3)](2) (4) and U(mu-SCS)(3)[Li(Et(2)O)](2) (6), respectively [SCS = (Ph(2)P = S)(2)C]. In THF, complex 4 was transformed into the mononuclear derivative (SCS)U(BH(4))(2)(THF)(2) (5). The multiple bond character of the uranium-carbon bond was first revealed by the X-ray crystal structures of the three complexes. The U=C bond in these complexes present a nucleophilic character, as shown by their reaction with a carbonyl derivative. Finally, DFT calculations prove the involvement of both 5f and 6d orbitals in both the sigma and the pi U-C bonds.

A bulky 1-phosphabarrelene, , was obtained from the reaction of a phosphinine with benzyne; two palladium complexes of were successfully employed in the Suzuki-Miyaura coupling of several aryl chlorides with phenylboronic acid at a relatively low catalyst loading, and activated aryl chlorides were coupled at room temperature in the absence of strong bases.