Ruthenium(0) complexes with triazolylidene spectator ligands: Oxidative activation for (de)hydrogenation catalysis

Cesari, Cristiana; Mazzoni, Rita; Müller‐Bunz, Helge; Albrecht, Martin

doi:10.1016/j.jorganchem.2015.02.022

Cited by 24 publications

(31 citation statements)

References 79 publications

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“…The dehydrogenation of benzylamine and related substrates was evaluated with complexes 1 and 2 under conditions similar to those reported for the oxidation of alcohols with related monofunctional triazolylidene complexes. Thus, a catalyst loading of 5 mol % in 1,2‐dichlorobenzene at 150 °C was used in the absence of an oxidant or a base . Under these conditions, both complexes 1 and 2 were active catalysts and converted primary amines into a mixture of secondary imines, secondary amines, and tertiary amines in different proportions.…”

Section: Resultsmentioning

confidence: 99%

“…[16,21,25] Under these conditions, both complexes 1 and 2 were active catalysts and converted primary amines into am ixture of secondary imines, secondary amines,a nd tertiary amines in different proportions. [16,21,25] Under these conditions, both complexes 1 and 2 were active catalysts and converted primary amines into am ixture of secondary imines, secondary amines,a nd tertiary amines in different proportions.…”

Section: Catalytic Experiments With Protic Substratesmentioning

confidence: 99%

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Triazolylidene‐Iridium Complexes with a Pendant Pyridyl Group for Cooperative Metal–Ligand Induced Catalytic Dehydrogenation of Amines

Valencia

Pereira

Müller‐Bunz

et al. 2017

Chemistry A European J

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Two iridium(III) complexes containing a C,N-bidentate pyridyl-triazolylidene ligand were prepared that are structurally very similar but differ in their pendant substituent. Whereas complex 1 contains a non-coordinating pyridyl unit, complex 2 has a phenyl group on the triazolylidene substituent. The presence of the basic pyridyl unit has distinct effects on the catalytic activity of the complex in the oxidative dehydrogenation of benzylic amines, inducing generally higher rates, higher selectivity towards formation of imines versus secondary amines, and notable quantities of tertiary amines when compared to the phenyl-functionalized analogue. The role of the pyridyl functionality has been elucidated from a set of stoichiometric experiments, which demonstrate hydrogen bonding between the pendant pyridyl unit and the amine protons of the substrate. Such N ⋅⋅⋅H-N interactions are demonstrated by X-ray diffraction analysis, H NMR, and IR spectroscopy, and suggest a pathway of substrate bond-activation that involves concerted substrate binding through the Lewis acidic iridium center and the Lewis basic pyridyl site appended to the triazolylidene ligand, in agreement with ligand-metal cooperative substrate activation.

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Section: Resultsmentioning

confidence: 99%

Section: Catalytic Experiments With Protic Substratesmentioning

confidence: 99%

Triazolylidene‐Iridium Complexes with a Pendant Pyridyl Group for Cooperative Metal–Ligand Induced Catalytic Dehydrogenation of Amines

Valencia

Pereira

Müller‐Bunz

et al. 2017

Chemistry A European J

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“…Novel iron complexes bearing both cyclopentadienone and Nheterocyclic carbene ancillary ligands have been obtained by a straightforward synthesis from Fe 2 (CO) 9 . The preparation represent a rare example of silver transmetallation involving iron.…”

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confidence: 99%

Straightforward synthesis of iron cyclopentadienone N-heterocyclic carbene complexes

et al. 2015

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“…Within the field of transfer hydrogenation, our group has recently developed novel ruthenium compounds for bifunctional catalysis [33,34] by combining cyclopentadienones, which cooperate with the metal centers in catalytic redox reactions [35][36][37][38], and N-heterocyclic carbenes (NHCs) [39,40], largely used and very versatile ligands due to their easy preparation and the tunability of their steric and electronic properties [41][42][43][44]. In particular, the reduction of the model compound 4fluoroacetophenone catalyzed by complexes 1a-c ( Figure 1) can be activated by addition of cerium ammonium nitrate (CAN), which favors the release of CO [34].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Reactivity of Poly(propyleneimine) Dendrimers Functionalized with Cyclopentadienone N-Heterocyclic-Carbene Ruthenium(0) Complexes

et al. 2020

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Ligand design in metal chemistry is a fundamental step when pursuing compounds with specific reactivity. In this paper, the functionalization of the OH group in the lateral chain of the N-heterocyclic-carbene (NHC) ligand bound to a bis-carbonyl cyclopentadienone NHC ruthenium(0) complex allowed the decoration of five generations of poly(propyleneimine) (PPIs) dendrimers with up to 64 organometallic moieties. The coupling was achieved by employing carbonyldiimidazole and the formation of carbamate linkages between dendritic peripheral NH2 and lateral OH groups on ruthenium complexes. The synthetic procedure, chemical purification, and spectroscopic characterization of the five generations of dendrimers (3g1–5) are here described. The ruthenium-modified dendrimers were activated as catalysts in the transfer hydrogenation of the model compound 4-fluoroacetophenone in the presence of cerium ammonium nitrate as their mononuclear congeners. The catalytic activity, being similar for the five generations, shows a decrease if compared to mononuclear complexes. This detrimental effect might be ascribed to the –CH2NH– functionalization, largely present in dendrimer skeleton and that can compete with the hydrogen transfer mechanism, but also partially to a dendritic effect caused by steric encumbrance.

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Ruthenium(0) complexes with triazolylidene spectator ligands: Oxidative activation for (de)hydrogenation catalysis

Cited by 24 publications

References 79 publications

Triazolylidene‐Iridium Complexes with a Pendant Pyridyl Group for Cooperative Metal–Ligand Induced Catalytic Dehydrogenation of Amines

Triazolylidene‐Iridium Complexes with a Pendant Pyridyl Group for Cooperative Metal–Ligand Induced Catalytic Dehydrogenation of Amines

Straightforward synthesis of iron cyclopentadienone N-heterocyclic carbene complexes

Synthesis and Reactivity of Poly(propyleneimine) Dendrimers Functionalized with Cyclopentadienone N-Heterocyclic-Carbene Ruthenium(0) Complexes

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