When Gold Cations Meet Polyoxometalates

International audienceMerging gold(I) cations with polyoxometalate anions results in various interclusters and complexes. Herein, the syntheses of these newly emerging gold(I)/polyoxometalate materials are reviewed. The applications of these promising hybrids in organic catalysis are also summarized and evaluated in terms of the advantages and limitations of the catalysts including efficiency, synergistic effects and recyclability

Synthesis of a square-planar rhodium alkylidene N-heterocyclic carbene complex and its reactivity toward alkenes

The first rhodium alkylidene square-planar complex stabilized by an N-heterocyclic carbene ligand, RhCl(-CHPh)(IPr)PPh3 (2; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-carbene), has been prepared by reaction of RhCl(IPr)(PPh3)2 (1) with phenyldiazomethane and its dynamic behavior in solution studied. Treatment of 2 with alkenes results in the formation of the ¿2-olefin complexes RhCl(¿2-CH2-CHR)(IPr)PPh3 (3, R = H; 4, R = Ph; 5, R = OEt) and new olefins arising from the coupling of the alkylidene with the alkenes, likely via a metallacyclobutane intermediate

Mono- and polynuclear Ag(I) complexes of N-functionalized bis(diphenylphosphino)amine DPPA-type ligands: synthesis, solid-state structures and reactivity

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Synthesis, Characterization, and Reactivity of Cationic Gold(I) r-Diimine Complexes

International audienceA series of cationic gold(I) R-diimine complexes of the type [(NHC)Au(R-diimine)]X or [(PPh3)Au(R- diimine)]X, where NHC = IPr, R-diimine = BIAN-dipp, X = PF6 (1); X = BF4 (2); X = SbF6 (3); NHC = ItBu, R-diimine = BIAN-dipp, X = PF6 (4); X = BF4 (5); NHC = IMes, R-diimine = BIAN-dipp, X = PF6 (6); PPh3, R-diimine = BIAN-dipp, X = PF6 (7); NHC = IPr, R-diimine = DAB-Mes, X = PF6 (8, 10) bearing an N-heterocyclic carbene (NHC) or a phosphine ligand, have been synthesized and characterized by NMR spectroscopy and single crystal X-ray diffraction. The stability of the new complexes and their catalytic activity for the intermolecular addition of the indole nucleophilic carbon to 1,6-enyne were also investigated

Silver(I) and copper(I) complexes with bis-NHC ligands : dinuclear complexes, cubanes and coordination polymers.

International audienceSilver(I) and copper(I) complexes containing neutral bis(N-heterocyclic carbene) (NHC) ligands and coordinated or non-coordinated chloride, bromide, iodide, or tetrafluoroborate anions, were synthesised. The nature of the anions impacts deeply the structural features of the complexes in the solid-state and neutral cubane-, neutral coordination polymer-, or dicationic bridged-type architectures have been characterised. The structures of (1,3-bis(3′-butylimidazol-2′-ylidene)benzene)disilver(I) dichloride (2a), bis(μ-1,3-bis(3′-butylimidazol-2′-ylidene)benzene-κ-C)tetra-μ3-bromotetrasilver(I) (2b), bis(1,3-bis(3′-butylimidazol-2′-ylidene)benzene)disilver(I) tetrafluoroborate (2d) in 2d·CH2Cl2, (1,3-bis(3′-butylimidazol-2′-ylidene)benzene)dicopper(I) dichloride (3a) and (1,3-bis(3′-butylimidazol-2′-ylidene)benzene)dicopper(I) dibromide (3b) were established by X-ray diffraction

Ring Opening Metathesis Polymerization(ROMP) ofcis- andtrans-3,4-Bis(acetyloxymethyl)cyclobut-1-enes and Synthesis of Block Copolymers

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Two‐Coordinate NHC‐Supported Zn II Organocations: Steric and Electronic Tunability and Use in Alkyne Hydroboration Catalysis

International audienceWe herein report on the synthesis, structure, and use in alkyne hydroboration catalysis of [(IPrCl)Zn−R]+ and [(ItBu)Zn−R]+ cations bearing IPrCl (IPrCl=1,3-bis[2,6-bis(1-methylethyl)phenyl]-4,5-dichloro-1,3-dihydro-imidazol-2-ylidene) and the sterically demanding ItBu carbene (ItBu=1,3-bis(1,1-dimethylethyl)−1,3-dihydro-imidazol-2-ylidene). Ionization of neutral precursors [(IPrCl)ZnR2] (1 a, R=Et; 1 b, R=Me) and [(ItBu)ZnEt2] (2) with one equivalent of [Ph3C][B(C6F5)4] led to with robust and stable two-coordinate ZnII cations [(IPrCl)Zn−R]+ (3 a, R=Et; 3 b, R=Me) and [(ItBu)Zn−Et]+ (4), respectively, all isolated as [B(C6F5)4]− salts. Further derivatization of alkyl cations 3 b and 4 by reaction with one equivalent of [B(C6F5)3] afforded cations [(IPrCl)Zn−C6F5]+ (5) and [(ItBu)Zn−C6F5]+ (6) as [B(C6F5)4]− salts, with cation 6 displaying a limited stability in solution. The molecular structures of cations 3 b, 4 and 5 were confirmed through X-ray diffraction studies. Among stable cations, Fluoride ion affinity (FIA) estimations agree with cation 5 being the most Lewis acidic in thus far reported [(IPrCl)Zn−R]+ cations. In the presence of pinacol borane and 1-octyne, cations 3 a–b, 5 and [(IPrCl)Zn−C6F5]+ (5 mol%) slowly catalyze the selective cis-hydroboration of 1-octyne to the vinylborane product A. Cation 5 also mediates 2-hexyne hydroboration to afford a mixture of hydroboration products B and C. In the case of hydroboration catalysis mediated by cations 5 and [(IPrCl)Zn−C6F5]+, experimental data and preliminary DFT calculations are consistent a Lewis-acid-type catalysis

Water-Soluble Gold–N-Heterocyclic Carbene Complexes for the Catalytic Homogeneous Acid- and Silver-Free Hydration of Hydrophilic Alkynes.

International audienceWater-soluble gold(III/I) N-heterocylic carbene complexes behave as efficient catalysts for the hydration of terminal alkynes in neat water. The transformation proceeds in the absence of Brønsted acids or halide scavengers and is suitable for sensitive substrates. Kinetic profiles and DFT studies provide a clear picture of intermediates present during catalysis