A selective catalytic meta sulfonation of 2-phenylpyridines was found to occur in the presence (arene)ruthenium(II) complexes upon reaction with sulfonyl chlorides. The 2-pyridyl group facilitates formation a stable Ru-C(aryl) σ bond that induces strong para-directing effect. Electrophilic aromatic substitution proceeds chloride furnish sulfone at position chelating group. This new process offers access atypical regioselectivity for reactions involving chelation-assisted cyclometalation.

The two-coordinate cationic Ni(I) bis-N-heterocyclic carbene complex [Ni(6-Mes)2]Br (1) [6-Mes =1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene] has been structurally characterized and displays a highly linear geometry with C-Ni-C angle of 179.27(13)°. Density functional theory calculations revealed that the five occupied metal-based orbitals are split in an approximate 2:1:2 pattern. Significant magnetic anisotropy results from this orbital degeneracy, leading to...

A series of ruthenium hydride N-alkyl heterocyclic carbene complexes has been investigated as catalysts for a tandem oxidation/Wittig/reduction reaction to give CC bonds from alcohols. The CH-activated complex Ru(IiPr2Me2)'(PPh3)2(CO)H (9) proves be the most active precursor catalyzing PhCH2OH and Ph3PCHCN in 3 h at 70 °C. These results provide (a) rare case which carbenes afford higher catalytic activity than their N-aryl counterparts (b) novel example importance NHC CH activation cycle.

Thermolysis of Ru(PPh3)3(CO)H2 with the N-heterocyclic carbene bis(1,3-(2,4,6-trimethylphenyl)imidazol-2-ylidene) (IMes) results in C-C activation an Ar-CH3 bond one mesityl rings ligand. Upon addition IMes to at room temperature presence alkene, C-H is observed instead. The thermodynamics these and cleavage reactions have been probed using density functional theory.

Ruthenium complexes have been shown to perform efficient transfer hydrogenation reactions between alcohols and alkenes; in combination with an situ Wittig reaction, indirect formation of C-C bonds has achieved from alcohols.

C−N bond activation of the N-heterocyclic carbene 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene occurs with Ru(PPh3)3(CO)HCl to give C-2 bound 1-isopropyl-4,5-dimethylimidazol-2-ylidene complex Ru(C−IiPrHMe2)(PPh3)2(CO)HCl via loss propene. In presence free carbene, this undergoes tautomerism corresponding imidazole compound Ru(N−IiPrHMe2)(PPh3)2(CO)HCl.

This perspective article focuses its attention on the most recent advances in hydrodefluorination processes catalyzed by late transition metal complexes, a field that has been matter of increasing interest during past decade. The evolution catalytic is treated giving precise information nature catalysts, reductants and fluoroorganic substrates have used until now. An overview mechanistic studies performed so far also given.

The catalytic hydrodefluorination (HDF) of hexafluorobenzene, pentafluorobenzene, and pentafluoropyridine with alkylsilanes is catalyzed by the ruthenium N-heterocyclic carbene (NHC) complexes Ru(NHC)(PPh3)2(CO)H2 (NHC = SIMes (1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene) 13, SIPr (1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) 14, IPr (1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) 15, IMes (1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene) 16). Catalytic activity follows...

A bit unusual: "Abnormal" carbene formation from a free monodentate N-heterocyclic occurs upon the room temperature reaction of [Ru3(CO)12] with 1,3-di-tert-butylimidazol-2-ylidene. Subsequent heating leads to CH activation at remaining C5 position afford μ3-bridging heterocycle, which is eliminated as imidazolium H2.

Abstract Comproportionation of [Ni(cod) 2 ] (cod=cyclooctadiene) and [Ni(PPh 3 ) X (X=Br, Cl) in the presence six‐, seven‐ eight‐membered ring N ‐aryl‐substituted heterocyclic carbenes (NHCs) provides a route to series isostructural three‐coordinate Ni I complexes [Ni(NHC)(PPh )X] Cl; NHC=6‐Mes 1 , 6‐Anis 6‐AnisMes 7‐ o ‐Tol 4 8‐Mes 5 8‐ 6 O‐8‐ 7 ). Continuous wave (CW) pulsed EPR measurements on reveal that spin Hamiltonian parameters are particularly sensitive changes NHC size,...

Reaction of the bulky 6-membered N-heterocyclic carbene 6-Mes with Ni(cod)2 gives a C–H activated nickel(II) complex, but novel three-coordinate Ni(I) species Ni(6-Mes)(PPh3)Br if reaction is performed in presence Ni(PPh3)2Br2. The complex precursor for catalytic hydrodehalogenation aryl halides.

A series of two-coordinate copper tert-butoxide complexes bearing five-, six-, and seven-membered ring N-heterocyclic carbenes, prepared by protonolysis (NHC)CuMes with tBuOH, have been used as catalytic precursors in the semihydrogenation alkynes silanes/tBuOH hydroboration HBPin. Both processes proceed high regioselectivity show enhancements six- carbenes.

Reaction of [Ru(IPr)2(CO)H]BAr(F)4 with ZnEt2 forms the heterobimetallic species [Ru(IPr)2(CO)ZnEt]BAr(F)4 (2), which features an unsupported Ru-Zn bond. 2 reacts H2 to give [Ru(IPr)2(CO)(η(2)-H2)(H)2ZnEt]BAr(F)4 (3) and [Ru(IPr)2(CO)(H)2ZnEt]BAr(F)4 (4). DFT calculations indicate that activation at proceeds via oxidative cleavage Ru concomitant hydride transfer Zn. can also activate hydridic E-H bonds (E = B, Si), computed mechanisms for facile H/H exchange processes observed in 3 4 are presented.

The dihydride ruthenium N-heterocyclic carbene complex Ru(IMes)(PPh3)2CO(H)2 (1) (IMes=1,3-dimesityl-1,3-dihydro-2H-imidazol-2-ylidene) is an efficient catalyst for both direct hydrogenation and transfer of ketones imines, in the absence base.

Alcohols have been employed as substrates for C-C bond-forming reactions which involve initial activation by the temporary removal of hydrogen to form an aldehyde. The intermediate aldehyde is converted into alkene via a Horner-Wadsworth-Emmons reaction, nitroaldol and aldol reactions. 'borrowed hydrogen' then returned bond.

Deuterium labeling studies indicate that base-induced intramolecular C-H activation in the agostic complex 2-D proceeds with exclusive removal of a proton from methyl arm an (i)Pr substituent on N-heterocyclic carbene (NHC) ligand. Computational show this alkyl bond reaction involves deprotonation one bonds is geminal to interaction, rather than itself. The readily accessible at room temperature, and computed barrier DeltaE (double dagger)(calcd) = +11.8 kcal/mol found when NHC...

A combination of experimental studies and density functional theory calculations is used to study C-N bond activation in a series ruthenium N-alkyl-substituted heterocyclic carbene (NHC) complexes. These show that prior C-H the NHC ligand renders system susceptible irreversible activation. In presence source HCl, activated Ru(I(i)Pr(2)Me(2))'(PPh(3))(2)(CO)H (1, I(i)Pr(2)Me(2) = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) reacts give Ru(I(i)PrHMe(2))(PPh(3))(2)(CO)HCl (2, I(i)PrHMe(2)...

Secret revealed: The mechanism of the catalytic hydrodefluorination pentafluorobenzene by N-heterocyclic carbene complex [Ru(IMes)(PPh3)2(CO)H2] has been investigated DFT calculations. Two sets novel pathways (concerted and stepwise) have defined whereby a Ru H ligand can act as nucleophile at fluoroarene substrate. most accessible pathway equates to formation 1,2,3,4-C6F4H2 thus accounts for unusual regioselectivity that is observed experimentally (see scheme). Detailed facts importance...

The photophysical properties of four, two-coordinate, linear diamidocarbene copper(i) complexes, [(DAC)2Cu][BF4] (1), (DAC)CuOSiPh3 (2), (DAC)CuC6F5 (3) and (DAC)Cu(2,4,6-Me3C6H2) (4) (DAC = 1,3-bis(2,4,6-trimethylphenyl)-5,5-dimethyl-4,6-diketopyrimidinyl-2-ylidene) have been investigated. Complex 1 shows a high photoluminescence quantum efficiency (ΦPL) in both the solid state (ΦPL 0.85) CH2Cl2 solution 0.65). emission band 1, as crystalline solution, is narrow (fwhm 2300 cm-1) relative to...

It has been previously demonstrated that stable singlet electrophilic carbenes can behave as metal surrogates in the activation of strong E–H bonds (E = H, B, N, Si, P), but it was believed these activations only proceed through an irreversible barrier. Herein we show that, is case with transition metals, steric environment be used to promote reductive elimination at carbon centers.