N-heterocyclic carbene ligands IMes (1), SIMes (2), IPr (3), SIPr (4), and ICy (5) react with Ni(CO)(4) to give the saturated tricarbonyl complexes Ni(CO)(3)(IMes) (8), Ni(CO)(3)(SIMes) (9), Ni(CO)(3)(IPr) (10), Ni(CO)(3)(SIPr) (11), Ni(CO)(3)(ICy) (12), respectively. The electronic properties of these have been compared their phosphine analogues general formula Ni(CO)(3)(PR(3)) by recording nu(CO) stretching frequencies. While all NHCs are better donors than tertiary phosphines, differences...

Reactivity and structural studies of unusual rhodium iridium systems bearing two N-heterocyclic carbene (NHC) ligands are presented. These capable intramolecular C-H bond activation lead to coordinatively unsaturated 16-electron complexes. The resulting complexes can be further by simple halide abstraction, leading 14-electron species an all-carbon environment. Saturation the vacant sites in 16- with carbon monoxide permits a comparison. DFT calculations show that these electrophilic metal...

The past decade has seen N-heterocyclic carbenes (NHC) emerging as a credible alternative to ubiquitous tertiary phosphines ligands in organic and organometallic chemistry. In many cases NHC have proven more effective than ancillary catalysis, while some they also enable unexpected welcomed chemical routes new products.(1) These initial discoveries paved the way continued search for NHCs able promote and/or unprecedented catalysis. Nevertheless, useful remains an arduous task, because, date,...

Abstract The current approach to improve and tune the enantioselective performances of transition‐metal catalysts for asymmetric synthesis is mostly focused modifications steric properties ancillary ligands active metal. Nevertheless, it also known that electrostatic effects can have a remarkable role promote selectivity in synthesis. Using Rh‐catalyzed 1,4‐addition phenylboronic acid 2‐cyclohexenone leading chiral 3‐phenylcyclohexanone as an example, we could show high enantioselectivity be...

A bis-sulfoxide with a binaphthyl backbone is introduced as readily available, chiral ligand entity in late-transition metal catalysis. Ligand p-tol-BINASO [where 1,1'-binaphthalene-2,2'-diyl-bis-(p-tolylsulfoxide)] obtained pure form one single synthetic step from relatively cheap, commercially available starting materials. Precatalyst [{(P,R,R)-p-tol-BINASO}RhCl]2 was synthesized high yield and structurally characterized by X-ray diffraction, structural data were compared to the free...

Modus operandi: Catalytic access to the title compounds through a new asymmetric α-arylation protocol is reported (see scheme). These products are formed in good yields and excellent enantioselectivities by using easily synthesized chiral N-heterocyclic carbene (NHC) ligand. Advanced DFT calculations reveal properties of NHC ligand mode operation catalyst. Detailed facts importance specialist readers published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or...

The synthesis and characterization of three- four-coordinate Ni(CO)n(NHC) (n = 2, 3; NHC N-heterocyclic carbene) complexes are reported. Reactions with CO the Ni(CO)2(NHC) lead to quantitative formation Ni(CO)4. Investigation this reaction under equilibrium conditions allows for determination Ni-NHC bond dissociation energies.

N-Heterocyclic carbene ligands derived from C(2)-symmetric diamines with naphthyl side chains are introduced as chiral monodentate ligands, and their palladium complexes (NHC)Pd(cin)Cl prepared. These compounds exist a mixture of diastereomers, the can be successfully separated absolute stereochemistry assigned. When used in asymmetric intramolecular alpha-arylation amides, oxindoles quaternary carbon centers obtained high yield selectivity when correctly matching chirality NHC complexes.

A new class of easily accessible and stable imidazolin-2-ylidenes has been synthesized where the side chains are comprised substituted naphthyl units. Introduction groups generates C 2 -symmetric ( rac) s- symmetric meso) atropisomers, interconversion between isomers is studied in detail both experimentally computationally. Complete characterization carbenes includes rare examples crystallographically characterized saturated NHC structures. Steric properties ligands an investigation their...

A new NHC·Pd-catalyzed asymmetric α-arylation of amides is reported that gives direct access to synthetically valuable, allylated oxindoles with quaternary carbon centers. The reaction made possible by the introduction a chiral NHC ligand. palladium complexes derived therefrom combine excellent reactivity high chemo- and enantioselectivity for title transformation.

From zero to hero? Sulfoxides are generally not considered useful ligand entities in asymmetric metal catalysis. However, a chiral disulfoxide as chelating the rhodium-catalyzed 1,4-addition of aryl boronic acids cyclic, alpha,beta-unsaturated ketones and esters gives impressive catalytic results, thus opening door future applications this new class.

Into the groove: The introduction of a C2-symmetric N-heterocyclic carbene ligand with appropriately substituted naphthyl side chains enables efficient Suzuki–Miyaura coupling to form bulky tetra-ortho-substituted biaryls from aryl bromides and chlorides at room temperature. DFT calculations uncover subtle steric phenomena play that lead superior catalytic performance. Cyoct=cyclooctyl. Detailed facts importance specialist readers are published as "Supporting Information". Such documents...

The solvent-dependent interaction of ItBu with a Rh(I)-olefin complex leads to the isolation two precursors en route unique double cyclometalation process. Abstraction chloride ligand from resulting enables "bare" 14-electron Rh(III) complex.

N-Dichlorophosphanyldibenzo[b,f]azepine (6) reacted with (−)-2,3-O-isopropylidene-d-threitol, (R)-taddol, (R,R)-diethyltartrate, (S)-binaphthol, α,α-diphenyl-l-prolinol, and (S)-proline to form the corresponding chiral P-alkene ligands 7−12. These were then used synthesize dinuclear chloro-bridged Rh(I) complexes 13−18 general formula [Rh(μ-Cl)(P-alkene)]2. It was shown by X-ray diffraction analyses that these P-alkenes indeed act as bidentate for Rh(I). Furthermore, crystal structures...

Abstract N‐heterocyclic carbene (NHC) ligands with naphthyl side chains were employed for the synthesis of unsaturated, yet isolable [(NHC)Ir(cod)] + (cod=1,5‐cyclooctadiene) complexes. These compounds are stabilised by an interaction aromatic wingtip that leads to a sideways tilt NHC−Ir bond. Detailed studies show how tilting such carbenes affects electronic shielding properties carbon atom and this is reflected significant upfield shifts in 13 C NMR signals. When intramolecular...

The synthesis and catalytic properties of Ni(II) complexes, with the general formula Ni(NHC)[P(OR)3](Ar)Cl is described. These complexes are air-stable extremely effective precatalysts in Suzuki-Miyaura cross-coupling reaction. reaction protocols described allow for aryl chlorides arylboronic acids, employing low catalyt-ic loading, to deliver a large variety functionalized biaryl compounds. For coupling N-heterocyclic boronic TBAF was used as an additive afford aryl-N-heterocyclic products....

The synthesis and catalytic properties of Ni(II) complexes with the general formula Ni(NHC)[P(OR)3](Ar)Cl is described. These are air‐stable extremely effective precatalysts in Suzuki‐Miyaura cross‐coupling reaction. reaction protocols described allow for aryl chlorides arylboronic acids, employing low loading, to deliver a large variety functionalized biaryl compounds. For coupling N‐heterocyclic boronic TBAF was used as an additive afford nitrogen‐containing products. Overall, these...

The synthesis and catalytic properties of Ni(II) complexes with the general formula Ni(NHC)[P(OR)3](Ar)Cl is described. These are air‐stable extremely effective precatalysts in Suzuki‐Miyaura cross‐coupling reaction. reaction protocols described allow for aryl chlorides arylboronic acids, employing low loading, to deliver a large variety functionalized biaryl compounds. For coupling N‐heterocyclic boronic TBAF was used as an additive afford nitrogen‐containing products. Overall, these...

[(COE)2M]+ fragments (M = Rh, Ir; COE cyclooctene) react with corannulene to give eta6-bound complexes [(COE)2Rh(eta6-C20H10)]PF6 and [(COE)2Ir(eta6-C20H10)]PF6. Both compounds were characterized by X-ray diffraction studies, binding in the solid state is compared that of their aromatic analogues [(COE)2M(eta6-arene)]PF6 (aryl benzene phenanthrene). Solution NMR studies show [(COE)2Rh]+ fragment walks over curved surface corannulene, whereas Ir analogue not fluxional. Experimental as well...

Two saturated N-heterocyclic carbene ligands with substituted naphthyl side chains were used for the preparation of Blechert-type ruthenium metathesis precatalysts. The resulting conformers complexes separated and unambiguously assigned by X-ray diffraction studies. All new compared in terms activity to original, SIMes-derived Blechert catalyst shown be superior. A study on impact solvent concentration RCM reactions using most active these catalysts ultimately led ring closing a variety...

Two equivalents of the chiral dibenz[b,f]azepine-derived P-alkene ligands 2−6 per metal afforded mononuclear Rh(I) and Cu(I) complexes that were used as catalysts for asymmetric conjugate addition reactions. Rh formed square-planar neutral (8−10) cationic (11, 12) general formulas [RhCl(κ1P-alkene)(κ2P-alkene)] cis-[Rh(κ2P-alkene)2][BF4], respectively (P-alkene = 2, 5, 6). In both cases reversible decoordination alkene function bidentate was observed in presence Lewis basic solvents, model...

Abstract A family of chiral C 2 ‐symmetric disulfoxide ligands possessing biaryl atropisomeric backbones has been synthesized by using the Andersen methodology. Complete characterization includes X‐ray crystallographic studies all and some their rhodium complexes. Their synthesis, optical purity, electronic properties, catalytic behavior in prototypical rhodium‐catalyzed 1,4‐addition phenylboronic acid to 2‐cyclohexen‐1‐one are presented through an depth study this ligand class. Density...

The introduction of N-heterocyclic carbene ligands that incorporate correctly substituted naphthyl side chains leads to increased activity and stability in second generation ruthenium metathesis catalysts.