Room temperature reversible C-H activation mediated by a Pt(0) center, and stoichiometric biphenyl formation via solvent activation.

International audienceRoom 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

The CO/PC analogy in coordination chemistry and catalysis

9 pagesThis short account summarizes recent results obtained in the coordination chemistry of phosphinines and emphasizes their analogy with CO ligands. Reduced complexes can be easily assembled through the reaction of reduced 2,2'-biphosphinine dianions with transition metal fragments. Theoretical calculations were performed to establish the oxidation state of the metal in these complexes. Though many reduced complexes are available, phosphinines proved to be too sensitive toward nucleophiles to be used as efficient ligands in most catalytic processes. However, the high electrophilicity of the phosphorus atom can be exploited to synthesize phosphacylohexadienyl anions which exhibit a surprising coordination chemistry. When phosphino sulfide groups are incorporated as ancillary tridentate anionic SPS ligands can be easily produced. These ligands can bind different transition metal fragments such as M-X (M = group 10 metal, X = halogen), Rh-L (L = 2 electron donor ligand), Cu-X and Au-X (X = halogen). Palladium(II) complexes proved to be active catalyst in the Miyaura cross-coupling reaction. Bidentate anionic PS ligands were also synthesized following a similar approach. Their Pd(II) (allyl) derivatives showed a very good activity in the Suzuki catalyzed cross-coupling process that allows the synthesis of biphenyl derivatives through the reaction of phenylboronic acid with bromoarenes

Insights into the mechanism for gold catalysis: behaviour of gold(i) amide complexes in solution

We report the synthesis and activity of new mononuclear and dinuclear gold amide complexes . The dinuclear complexes and were characterised by single crystal X-ray analysis. We also report solution NMR and freezing point depression experiments to rationalise their behaviour in solution and question the de-ligation process invoked in gold catalysis

Preparation of Tremorine and Gemini Surfactant Precursors with Cationic Ethynyl-Bridged Digold Catalysts

[EN] Tremorine and precursors of gemini surfactants were synthesised in a one-pot, three-step, double-catalytic A3 coupling reaction and characterised by structural and spectroscopic methods. The cationic [Au-I(L1)]SbF6 complex is a more active catalyst compared to neutral L2- and L3-Au-I bis(trifluoromethanesulfonyl) imidate complexes (L1, L2= Buchwald-type biaryl phosphane; L3= triphenylphosphine) in promoting the double A(3) coupling of ethynyltrimethylsilane, secondary amines (cyclic, aliphatic, or aromatic) and formaldehyde. The solvent influences the catalytic performance by desilylation of silyl acetylene or deactivation of the catalyst by a halide anion. Acetylide-bridged cationic di-gold(I) L1 and L2 complexes were isolated and characterised by means of single-crystal X-ray structure analysis and their spectroscopic properties. Iodine in the acetylene reagent deactivates the AuI catalyst by formation of the less active iodido-bridged cationic digold(I) L1 complex, which was fully characterised by single-crystal X-ray crystal structure analysis and spectroscopy. The nature of the phosphine ligand of the gold complexes used as catalyst affects the stability and activity of the formed cationic ethynyl-bridged Au-2(I)-L intermediates, isolation of which lends support to the proposed double A(3) coupling mechanism.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2015-69153-CO2-R1) and Generalidad Valenciana (Prometeo 2013-014) is gratefully acknowledged.Grirrane, A.; Alvarez-González, E.; García Gómez, H.; Corma Canós, A. (2017). Preparation of Tremorine and Gemini Surfactant Precursors with Cationic Ethynyl-Bridged Digold Catalysts. Chemistry - A European Journal. 23(12):2792-2801. https://doi.org/10.1002/chem.201605269S27922801231

A ruthenium(ii) bis(phosphinophosphinine) complex as a precatalyst for transfer-hydrogenation and hydrogen-borrowing reactions

The 2-phosphinophosphinine 2-PPh2-3-Me-6-SiMe3-PC5H2 (2) has been prepared and was shown to act as a κ2-chelating ligand in cis-[RuCl2(2)2] (4). Complex 4 was a competent precatalyst for the room temperature transfer hydrogenation of acetophenone (0.1 mol% 4 and 0.5 mol% KOtBu) and the conversion of methanol/ethanol mixtures to the advanced biofuel isobutanol in 50% yield and 96% selectivity

Strong Electronic and Counterion Effects on Geminal Digold Formation and Reactivity as Revealed by Gold(I)-Aryl Model Complexes

Die geminale Diaurierung von [Ph3PAu(Aryl)]‐Komplexen wurde als Modell untersucht, um Einblick in die intermediäre Bildung von geminalen diaurierten Gold(I)‐Vinylkomplexen in der Katalyse zu gewinnen (siehe Schema). Die Ergebnisse tragen zum Verständnis der Faktoren bei, die die Stabilität, Reaktivität und Dynamik dieser metallorganischen Zwischenstufen bestimmen