Synthesis and catalytic properties of novel ruthenium N-heterocyclic-carbene complexes (original) (raw)
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European Journal of Inorganic Chemistry, 2009
The reaction of RuCl2(PPh3)3 with tBuOK-deprotonated ortho-xylyl-bis(N-imidazolinium) salts 1a–d yields RuCl2(PPh3)[bis(imidazolidin-2-ylidene)] complexes (2a–d). Under similar conditions, [RuCl2(p-cymene)]2 leads to the ruthenium complex 3 containing a tridentate η6-arene-dicarbene ligand. All synthesized compounds were characterized byelemental analysis and NMR spectroscopy, and the molecular structures of 2a, 2b and 3 were determined by X-ray crystallography. The catalytic activity of RuCl2(PPh3)[bis(imidazolidin-2-ylidene)] complexes 2a–b was evaluated in the direct arylation of 2-phenylpyridine with chlorobenzene derivatives. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Synthesis and Catalytic Activity of Novel Benzimidazolinylidene-Ruthenium(II) Complexes
Synlett, 2010
The reaction of [RuCl 2 (p-cymene)] 2 with 1,3-dialkylbenzimidazolium salts 1a-d in the presence of a small excess of cesium carbonate yields chelated h 6 -arene, h 1 -carbene ruthenium complexes 2a-d. All compounds were characterized by elemental analysis, NMR spectroscopy and the molecular structures of two of the complexes were determined by X-ray crystallography. The catalytic activity of RuCl 2 (h 6 -arene, h 1 -benzimidazolinylidene) complexes was evaluated in the direct arylation of 2-phenylpyridine with bromobenzene derivatives.
European Journal of Inorganic Chemistry, 2019
A series of unsymmetrical 1,3-disubstituted benzimidazolium chlorides were synthesized as N-heterocyclic carbene (NHC) precursors. These compounds were used for synthesis of the new ruthenium(II) complexes of the type [RuCl2(arene)(NHC)], (arene = η 6-p-cymene). The structures of all compounds were characterized by 1 H NMR, 13 C NMR and FT-IR spectroscopy techniques. The catalytic activity of the ruthenium complexes has been evaluated with respect to the mono-Nalkylation reactions of aromatic amines with various alcohol derivatives under solvent-free conditions at 120 o C using the borrowing hydrogen strategy.
A series of water soluble arene-ruthenium(II) complexes [(η6-arene)RuCl(κ2-L)]n+ (n = 0, 1) ([Ru]-1 – [Ru]-12) containing pyridine based N,O or N,N ligands (L1-L6) were synthesized and employed for the catalytic C-H bond activation/ arylation of 2-phenylpyridine with aryl halides in water. Efficient C-H bond activation/ arylation of a wide range of substituted 2-phenylpyridines and aryl halides were achieved to afford corresponding mono and biarylated products. Exploring the reactivity of the synthesized complexes, our investigation with ruthenium catalysts inferred that pyridine based N,O donor ligands afforded enhanced catalytic activity compared to those obtained with the iminopyridine (N,N donor) ligands. Further, mass spectrometric investigations, during the catalytic and controlled reaction conditions, evidenced the presence of the crucial cycloruthenated species {(η6-p-cymene)Ru(κ2-CN-phenylpyridine)}+ (m/z [M+] 390.0), along with a ligand coordinated species, {(η6-p-cymene)R...
Organometallics, 2004
The new water-soluble complexes [RuXY(1butyl-3-methylimidazol-2-ylidene)(p-cymene)] n+ (X) Cl-, H 2 O; Y) Cl-, H 2 O, 1,3,5-triaza-7-phosphaadamantane (pta); n) 0-2) catalyze the hydrogenation of various olefins, aldehydes, and ketones and the redox isomerization of allyl alcohol in aqueous solution under mild conditions and are suitable for the modification of lipid membranes by catalytic hydrogenation.
Convenient syntheses of novel ruthenium catalysts bearing N-heterocyclic carbenes
Journal of Organometallic Chemistry, 2000
The 16-electron ruthenium(II) complexes Cp*Ru[C(R)N(H)C C(H)Ņ ¹¹¹¹¹¹¹¹¹º (R)]Cl (Cp* = h 5 -C 5 Me 5 ; R=Cy (ICy), 1a; Mes (IMes), 1b) containing N-heterocyclic carbenes are easily accessible in quantitative yields from [Cp*Ru(OMe)] 2 (Me= CH 3 ) and the corresponding 1,3-diorganylimidazolium chloride by methanol elimination. Compounds 1a-b can also be prepared in 75-80% yield by treating the commercially available polymeric ruthenium(III) compound [Cp*RuCl 2 ] n with the free 1,3-diorganylimidazolin-2-ylidenes in 1 to 1.5 molar amounts. 1a reacts with CO, PPh 3 , pyridine and ethyl diazoacetate (EDA) affording the 18-electron derivatives Cp*Ru(ICy)(L)Cl (L = CO, 2; PPh 3 , 3; py, 4; CHCO 2 Et, 5). The mixed dicarbene complex 5 is the first isolable ruthenium cyclopentadienyl species bearing a CHCO 2 Et moiety. Compounds 1a-b catalyze the carbon carbon coupling of terminal alkynes HC CR (R= Ph, SiMe 3 , t Bu, p-Tol) under mild conditions, with the selectivity strongly depending on the substituent R.
New Ruthenium(II) Complexes Bearing N - Heterocyclic Carbenes
Organometallics, 2002
N-heterocyclic carbene complexes of ruthenium(II), [CpRu(L*) 2 Cl] (2) and [CpRu(CO)(L*)-Cl] (3) (Cp ) η 5 -C 5 H 5 ; L* ) 1,3-dicyclohexyl-imidazolin-2-ylidene), have been obtained in high yields by reaction of [CpRu(PR 2 R′) 2 Cl] (R ) R′ ) Ph, 1a; R ) Ph, R′ ) 2-MeC 6 H 4 , 1b) and [CpRu(CO){PPh 2 (2-MeC 6 H 4 )}Cl] (1c), respectively, with the free carbene L*. The mixed dicarbene complex [CpRu(dCPh 2 )(L*)Cl] (4) is prepared from [CpRu(dCPh 2 ){PPh 2 (2-MeC 6 H 4 )}Cl] (1d) and an equimolar amount of L*, whereas subsequent reaction of 1d with L* leads to formation of 2, along with tetraphenylethene. The reaction of [Cp*Ru(PPh 3 ) 2 Cl] (1e) with L* gives the pentamethylcyclopentadienyl derivative [Cp*Ru(PPh 3 )(L*)Cl] (5) (Cp* ) η 5 -C 5 Me 5 ) by displacement of 1 equiv of PPh 3 . Complex 5 reacts in toluene with CO, pyridine (Py), and N 2 CHCO 2 Et, affording [Cp*Ru(CO)(L*)Cl] (6), [Cp*Ru(Py)(L*)Cl] , and the mixed dicarbene [Cp*Ru(dCHCO 2 Et)(L*)Cl] (8), which were isolated in high yields. The molecular structure of complex 6 has been determined by an X-ray investigation, and the carbene-ruthenium distance clearly indicates a single bond (2.0951(18) Å). The Nheterocyclic carbene does not undergo substitution by other two-electron ligands.
European Journal of Inorganic Chemistry, 2018
Six ruthenium(II) complexes with the general molecular formula [RuCl2(NHC)(η6‐p‐cymene)] (NHC = N‐heterocyclic carbene) were synthesized by the transmetalation method from [RuCl2(η6‐p‐cymene)]2 and silver(I)‐NHC complexes. All complexes were fully characterized by analytical and spectral methods (FT‐IR, elemental analysis and 1H and 13C NMR). The solid‐state structure of one of the ruthenium complexes [dichloro‐{1‐[2‐(2‐ethoxyphenoxy)ethyl]‐3‐(3,5‐dimethylbenzyl)benzimidazol‐2‐ylidene}(p‐cymene) ruthenium(II)] has been established by single‐crystal X‐ray diffraction study, which revealed that the ruthenium atom adopt a classical piano‐stool coordination geometry. Under the optimised conditions, these ruthenium complexes were found to be efficient catalysts for N‐alkylation of aniline with arylmethyl alcohols using the hydrogen borrowing strategy, which is a cost‐effective and environmentally attractive reaction for the preparation of N‐alkylated amines.
Journal of the Brazilian Chemical Society, 2007
Doze novos complexos hexacoordenados de rutênio(II) com amidas, [RuH(CO)(PPh 3) 2 (L 2)], foram sintetizados a partir do precursor [RuH 2 (CO)(PPh 3) 3 ]. Esses complexos foram caracterizados por análise elementar e por espectroscopias no UV-vis, no infravermelho e RMN de 1 H, 13 C e 31 P. Fórmulas moleculares e estruturas octaédricas foram propostas para os produtos. Os complexos mostraram-se eficientes na redução catalítica do grupo nitro em drogas do tipo cloranfenicol e metronidazol. Os rendimentos dos produtos de redução foram determinados espectrofotometricamente. Twelve new hexacoordinated ruthenium(II) complexes with organic amides, [RuH(CO)(PPh 3) 2 (L 2)], have been synthesized by treating the precursor, [RuH 2 (CO)(PPh 3) 3 ], with twelve different amide proligands separately. These complexes were characterized by elemental analysis and by UV-vis, IR, 1 H, 13 C and 31 P NMR spectroscopies. Molecular formulae and octahedral structures have been tentatively proposed for the products. These complexes were found to be efficient in the catalytic reduction of NO 2-containing drugs such as chloramphenicol and metronidazole to their amino derivatives. The percent yields of the reduction products were determined spectrophotometrically.