1,8‐Naphthyridine Revisited: Applications in Dimetal Chemistry

Bera, Jitendra K.; Sadhukhan, Nabanita; Majumdar, Moumita

doi:10.1002/ejic.200900312

Cited by 69 publications

(55 citation statements)

References 195 publications

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“…9 It was argued that the bridging arrangement of two PIN ligands would have steric repulsion between the ortho substitutents. 10 To test this hypothesis, we designed BIN devoid of a substitutent at C 7 (Scheme 2).…”

Section: ' Introductionmentioning

confidence: 99%

Site-Directed Anchoring of an N-Heterocyclic Carbene on a Dimetal Platform: Evaluation of a Pair of Diruthenium(I) Catalysts for Carbene-Transfer Reactions from Ethyl Diazoacetate

et al. 2011

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Site-directed anchoring of naphthyridine-functionalized N-heterocylic carbene (NHC) is achieved on a metal-metal singly bonded diruthenium(I) platform. Room-temperature treatment of 1-isopropyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazolium bromide (PIN 3 HBr) with Ru 2 (CH 3 COO) 2 (CO) 4 in acetonitrile affords the unsupported compound Ru 2 (CO) 4 (κ 2 C 2 ,N 1 -PIN) 2 Br 2 (1). Judicious alteration in the NHC ligand resulted in the bridged compound Ru 2 (CO) 4 (CH 3 COO)(μ 2 -κ 2 C 2 ,N 1 -BIN)Br (2) (BIN = 1-benzyl-3-(3-phenyl-1,8-naphthyrid-2-yl)imidazol-2-ylidene). X-ray analysis revealed the chelate binding of PIN on each ruthenium at equatorial sites for 1, and the bridge-chelate binding of BIN spanning the diruthenium core for 2. The catalytic utilities of the BAr F (tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) salts of these compounds are evaluated toward carbenetransfer reactions from ethyl diazoacetate including aldehyde olefination, cyclopropanation, and X-H (X = O, N) insertions. 1-BAr F is clearly shown to be the superior catalyst. DFT calculations are undertaken to understand the influence of NHC binding on the electronic structures of the "Ru 2 (CO) 4 " core and to rationalize the lower activity of 2-BAr F . ' INTRODUCTIONThe prospect of bimetallic synergy has been largely responsible for the utilization of metal-metal bonded compounds in organometallic catalysis. 1 Several dimetal compounds have gained prominence as catalysts for organic transformations. Incorporation of N-heterocylic carbene (NHC) is anticipated to boost the catalytic utilities of such compounds. 2 Toward this activity, axial binding of a bare NHC ligand to dirhodium(II) tetracarboxylates and dicobalt hexacarbonyls is reported. 3 Gios et al. have recently demonstrated that the reactivity of dirhodium(II) complexes can be tuned by attaching NHC ligands at sites trans to the Rh-Rh bond. 3b Equatorial anchoring of NHC on the dimetal core has been achieved by the application of bis-carbene ligands. The bitriazole-2-ylidene (bitz) is shown to form bridged dirhodium complex [Rh 2 (bitz) 2 (CH 3 CN) 6 ][BF 4 ] 4 (Scheme 1a). 4 Another variant, 1,1 0 -methylene-imidazole-2,2 0 -diylidene, bridges two chromium centers with a short metal-metal distance (Scheme 1b). 5 In both cases, mononuclear chelate complexes were isolated as well. Scrutiny of the current literature indicates an apparent lack of control for the directed synthesis of dimetal-NHC compounds.We sought to incorporate NHC on dimetal compounds. Sitespecific binding of ligands on a dimetal platform affords compounds having well-defined and accessible catalytic sites. Naphthyridinefunctionalized NHC ligands were chosen for this purpose owing to their multifaceted coordinating motifs and topological flexibility. 6 Herein we demonstrate the site-directed anchoring of heteroarenesubstituted NHC ligands PIN and BIN (Scheme 2) on the metalmetal singly bonded "[Ru 2 (CO) 4 ]" core. The unsupported chelate complex Ru 2 (CO) 4 (κ 2 C 2 ,N 1 -PIN) 2 Br 2 (1) and bridged complex Ru 2...

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Section: ' Introductionmentioning

confidence: 99%

Site-Directed Anchoring of an N-Heterocyclic Carbene on a Dimetal Platform: Evaluation of a Pair of Diruthenium(I) Catalysts for Carbene-Transfer Reactions from Ethyl Diazoacetate

et al. 2011

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“…The challenging task in designing a bimetallic catalyst is the selection of ligands that are capable of accommodating geometrical and electronic reorganization of the dimetal core during the course of the catalytic cycle. The demonstrated ability of 1,8‐naphthyridine (NP) to stabilize a host of dimetal cores prompted the utilization of the NP‐based ligand 7. A donor appendage (such as pyridyl, thiazolyl, pyrollyl) at the 2 position of the NP unit enables additional chelate‐ring formation and allows axial modulation of the metal–metal bond 8.…”

Section: Introductionmentioning

confidence: 99%

“…The demonstrated ability of 1,8-naphthyridine (NP) to stabilize a host of dimetal cores prompted the utilization of the NP-based ligand. [7] A donor appendage (such as pyridyl, thiazolyl, pyrollyl) at the 2 position of the NP unit enables additional chelate-ring formation and allows axial modulation of the metal-metal bond. [8] Coordination of 2-(2-thiazolyl)-1,8naphthyridine (tzNP) to a dimetal unit is shown in Scheme 1 a, as an illustrative example.…”

Section: Introductionmentioning

confidence: 99%

Bimetallic Catalysis Involving Dipalladium(I) and Diruthenium(I) Complexes

Das

Saha

Rahaman

et al. 2010

Chemistry A European J

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Dipalladium(I) and diruthenium(I) compounds bridged by two [{(5,7-dimethyl-1,8-naphthyridin-2-yl)amino}carbonyl]ferrocene (L) ligands have been synthesized. The X-ray structures of [Pd(2)L(2)][BF(4)](2) (1) and [Ru(2)L(2)(CO)(4)][BF(4)](2) (2) reveal dinuclear structures with short metal-metal distances. In both of these structures, naphthyridine bridges the dimetal unit, and the site trans to the metal-metal bond is occupied by weakly coordinating oxygen from the amido fragment. The catalytic utilities of these bimetallic compounds are evaluated. Compound 1 is an excellent catalyst for phosphine-free, Suzuki cross-coupling reactions of aryl bromides with arylboronic acids and provides high yields in short reaction times. Compound 1 is also found to be catalytically active for aryl chlorides, although the corresponding yields are lower. A bimetallic mechanism is proposed, which involves the oxidative addition of aryl bromide across the Pd-Pd bond and the bimetallic reductive elimination of the product. Compound 1 is also an efficient catalyst for the Heck cross-coupling of aryl bromides with styrenes. The mechanism for aldehyde olefination with ethyl diazoacetate (EDA) and PPh(3), catalyzed by 2, has been fully elucidated. It is demonstrated that 2 catalyzes the formation of phosphorane utilizing EDA and PPh(3), which subsequently reacts with aldehyde to produce a new olefin and phosphine oxide. The efficacy of bimetallic complexes in catalytic organic transformations is illustrated in this work.

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“…Shvo [175][176][177] and Gelman's [178][179][180][181][182][183] systems employ -OH unit for alcohol dehydrogenation reactions (Scheme 25d, e). There has been a continuing effort to design bifunctional catalysts on new molecular platforms [51,76,96,101,134,135,[184][185][186][187][188][189][190]. There has been a continuing effort to design bifunctional catalysts on new molecular platforms [51,76,96,101,134,135,[184][185][186][187][188][189][190].…”

Section: Alcohol Dehydrogenation At Axial Site Of a [Ru I -Ru I ] Bondmentioning

confidence: 99%

Homo- and Heterobimetallic Complexes in Catalysis

Kalck¹

2016

Topics in Organometallic Chemistry

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1,8‐Naphthyridine Revisited: Applications in Dimetal Chemistry

Cited by 69 publications

References 195 publications

Site-Directed Anchoring of an N-Heterocyclic Carbene on a Dimetal Platform: Evaluation of a Pair of Diruthenium(I) Catalysts for Carbene-Transfer Reactions from Ethyl Diazoacetate

Site-Directed Anchoring of an N-Heterocyclic Carbene on a Dimetal Platform: Evaluation of a Pair of Diruthenium(I) Catalysts for Carbene-Transfer Reactions from Ethyl Diazoacetate

Bimetallic Catalysis Involving Dipalladium(I) and Diruthenium(I) Complexes

Homo- and Heterobimetallic Complexes in Catalysis

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