A hexahydro-s-indacene based NHC ligand for olefin metathesis catalysts

Savka, Roman; Plenio, Herbert

doi:10.1016/j.jorganchem.2012.03.015

Cited by 24 publications

(11 citation statements)

References 44 publications

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“…Better yields of the respective Rh and Ir complexes were obtained by using the in situ generated Ag complex of carbene 4 as a mild NHC transfer reagent (Scheme 2). [14] The chloro complexes are converted into the closely related iodo complexes (X = I) by treatment of [(4)MCl(cod)] with an excess of KI. The NHC-Ag complex [(4)AgI] was also used for the synthesis of [(4)(SIMes)RuCl 2 (ind)] (Mes = mesitylene; ind = 3-phenyl-indeneylidene) according to a synthetic protocol reported by us for related complexes.…”

Section: Synthesis Of Ligands and Metal Complexesmentioning

confidence: 99%

Metal Complexes of a Boron‐Dipyrromethene (BODIPY)‐Tagged N‐Heterocyclic Carbene (NHC) as Luminescent Carbon Monoxide Chemodosimeters

Kos

Plenio

2014

Chemistry A European J

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Several metal complexes with a boron dipyrromethene (BODIPY)-functionalized N-heterocyclic carbene (NHC) ligand 4 were synthesized. The fluorescence in [(4)(SIMes)RuCl2(ind)] complex is quenched (Φ = 0.003), it is weak in [(4)PdI2(Clpy)] (Φ = 0.033), and strong in [(4)AuI] (Φ = 0.70). The BODIPY-tagged complexes can experience pronounced changes in the brightness of the fluorophore upon ligand-exchange and ligand-dissociation reactions. Complexes [(4)MX(1,5-cyclooctadiene)] (M = Rh, Ir; X = Cl, I; Φ = 0.008-0.016) are converted into strongly fluorescent complexes [(4)MX(CO)2] (Φ = 0.53-0.70) upon reaction with carbon monoxide. The unquenching of the Rh and Ir complexes appears to be a consequence of the decreased electron density at Rh or Ir in the carbonyl complexes. In contrast, the substitution of an iodo ligand in [(4)AuI] by an electron-rich thiolate decreases the brightness of the BODIPY fluorophore, rendering the BODIPY as a highly sensitive probe for changes in the coordination sphere of the transition metal.

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Section: Synthesis Of Ligands and Metal Complexesmentioning

confidence: 99%

Metal Complexes of a Boron‐Dipyrromethene (BODIPY)‐Tagged N‐Heterocyclic Carbene (NHC) as Luminescent Carbon Monoxide Chemodosimeters

Kos

Plenio

2014

Chemistry A European J

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“…A typical feature of the N ‐aryl and the imidazolylidene rings in SIMes‐type ligands is the orthogonality of the two ring planes . However, in the crystal structure of [IrCl(cod)( 8 b )], those two planes are tilted with an angle of approximately 60°, which appears to result from the presence of the two bulky triptycene groups and the cod ligand.…”

Section: Resultsmentioning

confidence: 75%

“…The crystal structure is highly indicative concerning the role of the triptycene ligand (Figure ). Iridium displays a typical square‐planar coordination geometry with a crystallographic mirror plane bisecting the molecule in the Cl−Ir−C(NHC) plane; bond lengths within the coordination sphere of Ir are normal . In the solid state, the two triptycene flaps are oriented in a syn ‐orientation.…”

Section: Resultsmentioning

confidence: 99%

Triptycene‐Based Chiral and meso‐N‐Heterocyclic Carbene Ligands and Metal Complexes

Savka

Bergmann

Kanai

et al. 2016

Chemistry A European J

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Based on 1-amino-4-hydroxy-triptycene, new saturated and unsaturated triptycene-NHC (N-heterocyclic carbene) ligands were synthesized from glyoxal-derived diimines. The respective carbenes were converted into metal complexes [(NHC)MX] (M=Cu, Ag, Au; X=Cl, Br) and [(NHC)MCl(cod)] (M=Rh, Ir; cod=1,5-cyclooctadiene) in good yields. The new azolium salts and metal complexes suffer from limited solubility in common organic solvents. Consequently, the introduction of solubilizing groups (such as 2-ethylhexyl or 1-hexyl by O-alkylation) is essential to render the complexes soluble. The triptycene unit infers special steric properties onto the metal complexes that enable the steric shielding of selected areas close to the metal center. Next, chiral and meso-triptycene based N-heterocyclic carbene ligands were prepared. The key step in the synthesis of the chiral ligand is the Buchwald-Hartwig amination of 1-bromo-4-butoxy-triptycene with (1S,2S)-1,2-diphenyl-1,2-diaminoethane, followed by cyclization to the azolinium salt with HC(OEt)3 . The analogous reaction with meso-1,2-diphenyl-1,2-diaminoethane provides the respective meso-azolinium salt. Both the chiral and meso-azolinium salts were converted into metal complexes including [(NHC)AuCl], [(NHC)RhCl(cod)], [(NHC)IrCl(cod)], and [(NHC)PdCl(allyl)]. An in situ prepared chiral copper complex was tested in the enantioselective borylation of α,β-unsaturated esters and found to give an excellent enantiomeric ratio (er close to 90:10).

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“…N-heterocyclic carbenes (NHCs) have attracted much attention, particularly for their ability to catalyze various important reactions such as metathesis, creation of furan, polymerization, hydrosilylation, hydrogenation, arylation, Suzuki-Miyaura cross-coupling and Mizoroki-Heck cross-coupling 1,2,3,4,5,6,7,8,9,10,11 . NHCs can be coupled with metals; such metal-NHC complexes have been extensively used in transition metalcatalyzed reactions as ancillary ligands and organocatalysts 12,13,14,15,16 .…”

Section: Introductionmentioning

confidence: 99%

Palladium <em>N</em>-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions

Sahin

Akkoς

Kayser

2017

JoVE

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Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from benzimidazolium salts. Detailed and generalized protocols are also presented for testing the catalytic activity of such complexes in arylation and Suzuki-Miyaura cross-coupling reactions. Representative results are shown for the catalytic activity of the four complexes in arylation and Suzuki-Miyaura type reactions. For each of the reactions investigated, at least one of the four complexes successfully catalyzed the reaction, qualifying them as promising candidates for catalysis of many carbon-carbon bond-forming reactions. The protocols presented are general enough to be adapted for the synthesis, purification and catalytic activity testing of new palladium N-heterocyclic carbene complexes.

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A hexahydro-s-indacene based NHC ligand for olefin metathesis catalysts

Cited by 24 publications

References 44 publications

Metal Complexes of a Boron‐Dipyrromethene (BODIPY)‐Tagged N‐Heterocyclic Carbene (NHC) as Luminescent Carbon Monoxide Chemodosimeters

Metal Complexes of a Boron‐Dipyrromethene (BODIPY)‐Tagged N‐Heterocyclic Carbene (NHC) as Luminescent Carbon Monoxide Chemodosimeters

Triptycene‐Based Chiral and meso‐N‐Heterocyclic Carbene Ligands and Metal Complexes

Palladium <em>N</em>-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions

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