The addition of aromatic formamidines to dihaloalkanes proceeds in air under mildly basic conditions and polar solvents afford the corresponding amidinium salts high yields. To demonstrate wide scope this methodology, several five-, six-, seven-membered saturated N-heterocyclic have been prepared. free carbenes 7-Mes, 7-Xyl, 7-Pri, 6-Mes, 6-Xyl also isolated as stable white solids, for first time solid state structures determined (7-Mes 7-Xyl). syntheses characterization their Ag(I) halide...

CO2 as feedstock: An air- and moisture-stable iridium(III) catalyst effectively promotes the hydrosilylation of CO2. This reaction leads to silyl formate in a highly selective manner proceeds efficiently under mild conditions, most likely by an outer-sphere mechanism, suggested theoretical calculations.

The synthesis of the novel seven-membered N-heterocyclic carbene (NHC) 1,3-dicyclohexyl-1,3-diazepan-2-ylidene (3) and its 5,6-dioxolane derivative 4 is reported their coordination chemistry with Rh(I), Ir(I), Pt(0) discussed. M(cod)(3)Cl, where M = Rh Ir, complexes display a high rotation barrier at room temperature about M−CNHC bond, whereas for M(CO)2(3)Cl Pt(nbe)2(3) rapid ligand observed ambient temperature. infrared ν(CO) values Rh(I) Ir(I) derivatives give measure donor ability new...

The synthesis of new functionalised 6- and 7-membered NHC (N-heterocyclic carbene) precursors bearing anisidyl or pyridine N-substituents, both symmetrically non-symmetrically substituted is reported. Their corresponding rhodium(i) iridium(i) complexes, M(COD)(NHC)Cl, were also prepared characterised. unusual Rh(iii)/Rh(i) salt, [Rh(eta(2)-NHC-py)(2)Cl(2)][Rh(COD)Cl(2)], was obtained with one the pyridyl-functionalised ligands. Single-crystal X-ray analyses have been for majority complexes...

The β-Z selectivity in the hydrosilylation of terminal alkynes has been hitherto explained by introduction isomerisation steps classical mechanisms. DFT calculations and experimental observations on system [M(I)2{κ-C,C,O,O-(bis-NHC)}]BF4 (M=Ir (3a), Rh (3b); bis-NHC=methylenebis(N-2-methoxyethyl)imidazole-2-ylidene) support a new mechanism, alternative to postulations, based an outer-sphere model. Heterolytic splitting silane molecule metal centre acetone (solvent) affords hydride...

The dehydrogenation of formic acid permits the production hydrogen virtually free carbon monoxide, which is a key requisite for its use in fuel cells. Moreover, HCOOH suitable carrier, better several crucial characteristics than other liquid organic carriers, namely, low toxicity, high content and recyclability (via CO 2 hydrogenation). most successfully employed catalysts are those based on Ir, Ru, Rh, Fe metal centers. catalytic cycles through homogeneous complexes operate show wide...

Abstract The rhodium complexes [Rh(NHC)(COD)Cl] and cis ‐[Rh(NHC)(CO) 2 Cl] of seven‐membered N‐heterocyclic carbenes (NHC) bearing aromatic N‐substituents (mesityl, xylyl o ‐tolyl) were synthesised, a comparison their steric electronic properties with those the analogous five‐ six‐membered NHC was made on basis infrared solid‐state data. X‐ray structures for Rh(6‐Mes)(COD)Cl, Rh(7‐Mes)(COD)Cl Rh(7‐ Tol)(COD)Cl determined.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Abnormal isoxazolylidene complexes, a new subclass of mesoionic complexes containing an isoxazolium-derived carbene type ligand, have been synthesised via oxidative addition and compared to structurally related by using (31)P NMR spectroscopy as convenient probe for their donor ability in catalytic cross-coupling reactions.

Breaking ties: Recent reports on iridium and ruthenium homogeneous hydrosilylation catalysis point to a heterolytic activation of SiH bonds promoted by the oxophilicity silicon atom Lewis acidity metal center. This unusual type mechanism opens door more widespread use catalysts that operate an ionic or concerted outer-sphere in organic synthesis.

A synthon for a 14-electron Ir(III) species is described. The geometrical control exerted by the ligand system over Ir–alkenyl intermediate in hydrosilylation of terminal alkynes precludes formation more thermodynamically stable β-(E)-vinylsilane, thus affording β-(Z) isomer excellent yields.

Abstract Recent reports on homogeneous catalytic transformation of carbon dioxide by iridium complexes have prompted us to review the area. Progress new catalysts for transformations should take into account interaction with center, which seems be governed oxidation state and nature molecule. Most examples catalyzed reductions are based Ir III centers. These reactions place through outer‐sphere mechanisms, means nucleophilic attack atom. In all reported systems, nucleophile is always a...

The catalytic activity in the hydrosilylation of terminal alkynes by unsaturated hydrido iridium(III) compound [IrH(κ3-hqca)(coe)] (1), which contains rigid asymmetrical dianionic ONO pincer ligand 8-oxidoquinoline-2-carboxylate, has been studied. A range aliphatic and aromatic 1-alkynes efficiently reduced using various hydrosilanes. Hydrosilylation linear hex-1-yne oct-1-yne gives a good selectivity toward β-(Z)-vinylsilane product, while for bulkier t-Bu-C≡CH reverse β-(E)-vinylsilane...

New [Ir(CH3CN)2(I)2{κC,C′-bis(NHC)}]BF4 complexes featuring bis-NHC ligands with a methylene bridge and different N substitution (−CH2CH2CH2CH3 −CH2CH2OPh) were synthesized. NMR studies X-ray diffraction structures evidenced that the wingtip group −CH2CH2OPh presents hemilabile behavior in solution, oxygen atom coordinating dissociating at room temperature, which contrasts strong coordination of ether functions complex [Ir(I)2{κC,C′,O,O′-bis(NHCOMe)}]BF4 (bis(NHCOMe) =...

This study prospectively investigates the potential influence of low-dose aspirin on blood pressure in pregnant women who were at a higher risk developing preeclampsia than that general obstetric population and received different times day according to their rest-activity cycle. A double-blind, randomized, controlled trial was conducted 341 (181 primipara) randomly assigned 1 6 possible groups treatment (either placebo or aspirin, 100 mg/day, starting 12 16 weeks gestation) time treatment:...

Abstract The performances of a number Rh I and Ir complexes type [M(NHC)(COD)Cl] in the transfer hydrogenation ketones were tested under variety reaction conditions, with substrates, allowing comparison Rh‐ Ir‐NHC complexes, also influence NHC ligand on catalytic performance. Notably, symmetrically substituted NHCs only those bearing cyclohexyl substituents active, saturated 5‐, 6‐ 7‐NHCs N‐Mes substituents, [Rh(5,6,7‐Mes)(COD)Cl], showing no activity test conditions. unsymmetrical o...

Better together: A novel hybrid N-heterocyclic carbene (NHC) palladium complex, integrating a totally inorganic and polyanionic decatungstate unit, has been synthesized following convergent strategy. The interplay of the Pd binding domains with scaffold is instrumental in accessing multi-turnover catalysis CC cross-coupling aromatic dehalogenation reactions under MW-assisted protocols (see scheme). Detailed facts importance to specialist readers are published as "Supporting Information"....

Developments in palladium chemistry have been spurred predominantly by the outstanding application potential of this metal catalysis. The quest for new ligands order to modulate catalytic activity and selectivity center has greatly stimulated discovery N-heterocyclic carbenes as formally neutral, strongly donating, covalently binding ligands. Abnormal variations carbenes, even though known (yet not recognized) 30 years, received very little attention until recently. In parts may due fact...

A well-defined NHC-Ir(iii) catalyst, [Ir(H)2(IPr)(py)3][BF4] (IPr = 1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene), that provides access to a wide range of aryl- and heteroaryl-silanes by intermolecular dehydrogenative C-H bond silylation has been prepared fully characterized. The directed non-directed functionalisation bonds accomplished successfully using an arene as the limiting reagent variety hydrosilanes in excess, including Et3SiH, Ph2MeSiH, PhMe2SiH, Ph3SiH (EtO)3SiH. Examples...

Abstract We describe a bis‐N‐heterocyclic carbene rhodium(III) complex, featuring two trifluoroacetato ligands, that affords variety of α‐vinylsilanes in good yields by hydrosilylation terminal alkynes. Selectivities around 7:1 α/β‐( E ) were reached, while the β‐( Z product was only marginally obtained. This example sharply contrasts with )‐selectivity observed for its parent diiodido complex magnified image

The Ir(i) complexes [Ir(cod)(κP,C,P'-NHO(PPh2))]PF6 and [IrCl(cod)(κC-NHO(OMe))] (cod = 1,5-cyclooctadiene, NHO(PPh2) 1,3-bis(2-(diphenylphosphanyl)ethyl)-2-methyleneimidazoline) NHO(OMe) 1,3-bis(2-(methoxyethyl)-2-methyleneimidazoline), both featuring an N-heterocyclic olefin ligand (NHO), have been tested in the transfer hydrogenation reaction; this representing first example of use NHOs as ancillary ligands catalysis. pre-catalyst has shown excellent activities aldehydes, ketones imines...

The [2+2+2] cycloaddition of alkynes and nitriles is an efficient atom-economic method for the synthesis pyridines. However, most examples so far reported entail use of...

The dehydrogenative coupling of hydrosilanes with alcohols or water is a fundamental transformation in organosilicon chemistry, enabling the synthesis alkoxysilanes, silanols, and siloxanes—key materials for coatings adhesives. Traditionally, these reactions have relied on catalysts based platinum‐group metals (PGMs), which are costly scarce. development Earth‐abundant metal (EAM) offers sustainable cost‐effective alternative. This concept article highlights recent advancements homogeneous...

A new PCP-type ligand based on an N-heterocyclic olefin (NHO) scaffold has been prepared. The flexibility of this ligand, which is able to adopt facial coordination modes in Ir(I) or meridional Ir(III) complexes, can be attributed the dual nature (ylide-olefin) NHO scaffold. This results a rare case "slippage" that supported by X-ray crystallography and DFT calculations.