Well-defined iron bis(diphosphine) complexes are active catalysts for the dehydrogenative C-H borylation of aromatic and heteroaromatic derivatives with pinacolborane. The corresponding borylated compounds were isolated in moderate to good yields (25-73%) with a 5 mol% catalyst loading under UV irradiation (350 nm) at room temperature. Stoichiometric reactivity studies and isolation of an original trans-hydrido(boryl)iron complex, Fe(H)(Bpin)(dmpe)2, allowed us to propose a mechanism showing the role of some key catalytic species.

International audienceThe cobalt carbonyl [Co2(CO)8] complex is employed as a useful catalyst for the reduction of tertiary amides to the corresponding tertiary amines using 1,1,3,3-tetramethyldisiloxane (TMDS) and poly(methylhydrosiloxane) (PMHS) as silane reagents under thermal (100 °C) or photo-assisted conditions (UV, 350 nm at room temperature). Of particular interest, a low catalytic amount (0.5 mol%) of [Co2(CO)8] is used to perform the reaction with 2.2 equiv. of PMHS at 100 °C for 3 h. This reaction is the first example of a cobalt-catalyzed hydrosilylation of amides

The p-methoxybenzyl protecting group (PMB) on various alcohols and an acid was efficiently and selectively cleaved by the action of a catalytic amount of silver(I) hexafluoroantimonate combined with 0.5 equiv of 1,3,5-trimethoxybenzene in dichloromethane at 40 °C.

The backbone-functionalized anionic carbenes maloNHC (1 R ; malonate backbone) and imidNHC (2; imidate backbone) were generated in situ from their respective zwitterionic precursors and treated with FeCp(CO) 2 I to afford the zwitterionic complexes {FeCp(CO) 2 (1 R )} (3 R ; 59−84% yield), and {FeCp(CO) 2 (2)} (4; 77% yield), respectively. Methylation of the malonate complex 3 Me takes place at one of the backbone oxygen atoms to give the cationic adduct [FeCp(CO) 2 (1 Me Me )](OTf) ([5 Me ](OTf); 96% yield), whereas methylation of 4 takes place at the imidate nitrogen atom to produce the cationic adduct [FeCp(CO) 2 (2 Me )](OTf) ([6 Me ](OTf); 84% yield). All of the complexes were characterized by NMR and IR in solution, while X-ray structure analyses were carried out for 3 Me , 4, and [6 Me ](OTf). In addition, a detailed experimental and theoretical investigation of the electron density within the archetypal zwitterionic complex 3 Me was carried out. The observation of short intramolecular contacts between C ipso or C ortho of the mesityl groups of the carbene and the proximal carbonyl groups is rationalized in terms of a noncovalent "through space" π−π* interaction involving a two-electron delocalization of the occupied π(C ipso C ortho ) molecular orbital (MO) of the aryl ring into one vacant π*(CO) MO of the carbonyl ligand. A theoretical analysis carried out on dissymmetrical model complexes reveals that the magnitude of such an interaction is correlated with the donor properties of aryl group substituents. A catalyst screening of the above complexes in the hydrosilylation of benzaldehyde under visible light irradiation revealed a dramatic effect of the electronic donor properties of these carbenes on the performances of their complexes, with the more nucleophilic carbene 1 tBu − in the zwitterionic species 3 tBu appearing as the most efficient. This complex shows good efficiency and excellent chemoselectivity in the hydrosilylation of various aldehydes bearing reactive functional groups. It is also moderately active in the hydrosilylation of a few ketone substrates and exhibits very good performance in the hydrosilylation of representative aldimines and ketimines.

Substituted α-pyrones were straightforwardly synthesized in good to excellent yields by a new gold(I)-catalyzed rearrangement of β-alkynylpropiolactones.

Fluorescent nanohybrids, based on p-extended hydroxyoxophosphole ligands grafted onto ZnO nanoparticles, were designed and studied. The restriction of the intramolecular motions of the organic fluorophore, through either aggregates' formation in solution or processing into thin films, forms highly emissive materials due to a strong Aggregation Induced Emission effect. Theoretical calculations and XPS analyses were performed to analyze the interactions between the organic and inorganic counterparts. Preliminary results on the use of these nanohybrids as solution-processed emissive layers in Organic Light Emitting Diodes (OLEDs) illustrate their potential for lighting applications.

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Iron-Catalyzed C-H Borylation of Arenes. -Both aromatic and heteroaromatic arenes undergo dehydrogenative borylation with pinacolborane catalyzed by well--defined iron bis(diphosphine) complexes under UV irradiation. A possible mechanism is proposed based on an isolated hydrido(boryl)iron complex synthesized from pinacolborane and stoichiometric amount catalyst. -(DOMBRAY, T.; WERNCKE, C. G.; JIANG, S.; GRELLIER, M.; VENDIER, L.; BONTEMPS, S.; SORTAIS, J.-B.; SABO-ETIENNE, S.; DARCEL*, C.; J. Am. Chem. Soc. 137 (2015) 12, 4062-4065, http://dx.doi.org/10.1021/jacs.5b00895 ; Inst. Sci. Chim., CNRS, Univ. Rennes, F-35042 Rennes, Fr.; Eng.) -L. Grundl 35-215