Syntheses, x-ray crystal structures, and fluxional behavior of the clusters Cp*3Co3(.mu.2-CO)(.mu.3-CO)(.mu.-H)2, Cp*3Co3(.mu.-H)(.mu.3-.eta.2-HC:NCMe3), and Cp*3Co3(.mu.2-H)(.mu.3-.eta.2-HC:NCMe2CH2Me)

Casey, Charles P.; Widenhoefer, Ross A.; Hallenbeck, Susan L.; Hayashi, Randy K.; Gavney, James A.

doi:10.1021/om00024a018

Cited by 21 publications

(11 citation statements)

References 2 publications

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“…These successive pivot motions cause the environments of the Cp* groups to be equivalent. The successive pivot motions of the μ 3 -η 2 (//)-imidoyl ligand on its M−C and M−N bonds on a trimetallic plane have been clearly elucidated in (Cp*Co) 3 (μ-H)(μ 3 -η 2 -HCNCMe 3 ) 17 and Ru 3 (CO) 9 (μ-H)(μ 3 -η 2 -MeCNMe), 18 but that of a μ-pyridyl group has not been reported so far.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Synthesis of Triruthenium Complexes Containing a Triply Bridging Pyridyl Ligand and Its Transformations to Face-Capping Pyridine and Perpendicularly Coordinated Pyridyl Ligands

et al. 2012

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Unlike the reactions of carbonyl clusters with pyridine leading to the formation of μ-pyridyl complexes, the reaction of the triruthenium pentahydrido complex {Cp*Ru-(μ-H)} 3 (μ 3 -H) 2 (Cp* = η 5 -C 5 Me 5 ) (1) with pyridines provided μ 3 -η 2 (//)-pyridyl complexes, (Cp*Ru) 3 (μ-H) 4 (μ 3 -η 2 (//)-RC 5 H 3 N) (2a, R = H; 2b, R = 4-COOMe; 2c, R = 4-COOEt; 2d, R = 4-Me; 2e, R = 5-Me), in which the molecular plane of the pyridyl group was tilted with respect to the Ru 3 plane. Electron-rich metal centers of the trimetallic core enabled back-donation to the pyridyl group, which caused the additional π-coordination of the CN bond. The electron-rich metal centers of 2a−2c also promoted further transformation into face-capping pyridine complexes {Cp*Ru(μ-H)} 3 (μ 3 -η 2 :η 2 :η 2 -RC 5 H 4 N) (3a, R = H; 3b, R = 4-COOMe; 3c, R = 4-COOEt) upon heating. In contrast, the thermolysis of 2d did not afford a face-capping picoline complex because of the poor electronaccepting ability of the picolyl moiety. Instead, the coordinatively unsaturated μ 3 -picolyl complex (Cp*Ru) 3 (μ-H) 2 (μ 3 -η 2 -4-Me-C 5 H 3 N) (4d) was obtained. Owing to its unsaturated nature, 4d can react with γ-picoline to yield 4,4′-dimethyl-2,2′-bipyridine. Although the reaction rate was slow, complex 1 catalyzed the dehydrogenative coupling of 4-substituted pyridines containing an electron-donating group. The protonation of 2a also afforded the coordinatively unsaturated pyridyl complex [(Cp*Ru) 3 (μ-H) 2 (μ 3 -H)(μ 3 -η 2 :η 2 (⊥)-C 5 H 4 N)] + (5a), but the coordination mode of the pyridyl group in 5a was completely different from that in 4d. The pyridyl moiety in 5a was coordinated on one of the Ru−Ru bonds in a perpendicular fashion. The methylation of the face-capping pyridine complex 3a, which led to the formation of the N-methyl pyridinium complex [(Cp*Ru) 3 (μ-H) 3 (μ 3 -η 2 :η 2 :η 2 -C 5 H 5 NMe)] + (7b) was also examined. NMR studies on 7b as well as X-ray diffraction studies suggested enhanced backdonation to the pyridinium moiety because of the localized cationic charge on the nitrogen atom. ■ INTRODUCTIONThe chemistry of organic molecules on a metal surface has attracted considerable attention in relation to heterogeneous catalysis. The interaction of an aromatic compound with a metal surface is one of the most intensively studied subjects in this area, and various adsorption modes of arenes have thus far been elucidated by means of high-resolution electron energy loss spectroscopy (HREELS), low-energy electron diffraction (LEED) study, scanning probe microscopy (SPM), and so on. 1 For example, Somorjai and co-workers used LEED to elucidate that benzene is adsorbed on a 3-fold site of Rh(111) in a flat manner with respect to the surface in the presence of CO. 1b In contrast to benzene, pyridine can interact with a metal surface by both π electrons and the lone-pair electrons at the nitrogen atom. This produces the interesting chemistry of chemisorbed pyridine, in which the pyridine is converted from a relatively flat-lying π-bonded s...

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Section: ■ Results and Discussionmentioning

confidence: 99%

Synthesis of Triruthenium Complexes Containing a Triply Bridging Pyridyl Ligand and Its Transformations to Face-Capping Pyridine and Perpendicularly Coordinated Pyridyl Ligands

et al. 2012

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“…Casey et al showed that site exchange between μ-CO and μ 3 -CO ligands in (Cp*Co) 3 (μ-H) 2 (μ-CO)(μ 3 -CO) occurs on the NMR time scale . Thus, the migration of the μ-CO ligand via a face-capping CO seems to be reasonable (Scheme ).…”

Section: Results and Discussionmentioning

confidence: 99%

Synthesis of an Electron-Deficient Triruthenium Hydrido Complex Having a Bridging Carbonyl Ligand: Influence of a CO Ligand on the Properties and Reactivities of a Hydrido Cluster

et al. 2017

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A novel triruthenium hydrido cluster, (Cp*Ru)3(μ3-H)(μ-H)2(μ-CO) (4; Cp* = η5-C5Me5), having a bridging CO ligand was synthesized by the reaction of {Cp*Ru(μ-H)}3(μ3-O) (3) with methanol. Upon introduction of a CO ligand, the cyclic voltammogram of 4 demonstrated a significant shift of the redox potential in the positive direction in comparison to a pentahydrido complex, {Cp*Ru(μ-H)}3(μ3-H)2 (1), which adopts the same 44-electron configuration. Owing to its coordinatively unsaturated nature, 4 readily reacted with butadiene, terminal alkynes, and alkenes similarly to the parent pentahydrido complex 1. However, the reactivity was slightly different from that of 1, and the influence of the CO ligand at the triruthenium site was evaluated by the reaction of various unsaturated hydrocarbons. The reaction of 4 with 1,3-dienes yielded a diene adduct, {Cp*Ru(μ-H)}3(μ-η2:η2-s-cis-H2CCRCHCH2)(CO) (5a, R = H; 5b, R = Me) without elimination of dihydrogen. In the same manner as for 1, 4 reacted with phenylacetylene to yield a μ3-η2:η2(⊥)-alkyne complex, (Cp*Ru)3(μ-H){μ3-η2:η2(⊥)-PhCCH}(μ3-CO) (7a); in contrast, an isomeric μ3-pentenylidene complex, (Cp*Ru)3(μ-H){μ3-η2-CC(nPr)H}(μ-CO) (9b), was obtained by reaction with 1-pentyne. A series of products was obtained by the reaction of 4 with ethylene molecules. A μ3-ethylidyne complex, (Cp*Ru)3(μ-H)2(μ3-CMe)(μ-CO) (11), was initially formed, accompanied by the formation of ethane at ambient temperature. The treatment of 11 with ethylene resulted in the removal of hydrido ligands, affording a μ3-vinylidene complex, (Cp*Ru)3(μ-H)(μ3-η2-CCH2)(μ-CO) (9a). At higher temperatures, a second ethylene molecule was incorporated in the triruthenium plane and an equilibrated mixture of a μ3-ethylidyne−μ-ethylidyne complex, (Cp*Ru)3(μ-H)(μ-CMe)(μ3-CMe)(μ-CO) (13), and μ3-ethylidyne−μ-vinyl complex, (Cp*Ru)3(μ-H)(μ3-CMe)(μ-η2-CHCH2)(μ-CO) (12), was obtained. The formation of a μ3-η3-C3 ring on the Ru3 plane was observed upon the thermolysis of the equilibrated mixture at 180 °C, which clearly demonstrates the coupling of the two C2 moieties placed on each face of the triruthenium plane.

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“…Although a square-planar coordination is expected to occur, a tetrahedral environment (Chart ) is proposed on the basis of both the chemical behavior (vide infra) and the structure found for the related iridium complex [CpTi(μ 3 -S) 3 Ir 3 (μ-CO)(CO) 3 {(POMe) 3 } 3 ], which has recently been characterized 10a. Since the scrambling of carbonyl ligands in cluster chemistry generally proceeds via a series of terminal-to-bridge carbonyl sequences, the dynamic behavior could take place through a concerted movement of the carbonyl ligands underneath the triangle defined by the three rhodium atoms. A standard merry-go-round exchange process involving the motion of the bridging μ 2 -CO ligand to a terminal position at one rhodium center, accompanied by the conversion of its terminal carbonyl ligand to bridge the adjacent rhodium atom, is the proposed exchange mechanism (Figure ).…”

Section: Resultsmentioning

confidence: 99%

Early−Late Heterotetranuclear Complexes (TiRh₃) with Bridging Sulfido Ligands: Ligand Replacement Reactions and Catalytic Activity in Hydroformylation of Olefins

Pérez‐Torrente¹,

Ciriano²,

Oro³

et al. 1999

Organometallics

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The tetranuclear early−late heterobimetallic (TiRh3) complexes [CpTi(μ3-S)3{Rh(diolef)}3] (diolef = tfbb (1), cod (2)) in the presence of P-donor ligands are active precursors in the hydroformylation of hex-1-ene and styrene under mild conditions of pressure and temperature. A 96% conversion to aldehydes and 77% regioselectivity for the linear aldehyde is obtained in the hydroformylation of hex-1-ene using PPh3 (P/Rh = 2−4) as the P-donor ligand at 5 bar and 353 K. Hydroformylation of styrene under similar conditions (10 bar) gives 70% conversion and 88% regioselectivity in favor of 2-phenylpropanal. The reaction of [CpTi(μ3-S)3{Rh(CO)2}3] (3) with monodentate P-donor ligands results in the selective synthesis of the C 3 isomer of the complexes [CpTi(μ3-S)3Rh3(CO)3(PR3)3]. The compound [CpTi(μ3-S)3Rh3(CO)3(PPh3)3] (5) reacts reversibly with carbon monoxide to give the 62-electron valence clusters [CpTi(μ3-S)3Rh3(μ-CO)(CO)4(PPh3)2] (4b) and [CpTi(μ3-S)3Rh3(μ-CO)(CO)3(PPh3)3] (4c), which are in equilibrium. High-pressure NMR spectroscopic studies have shown that both clusters are also formed under hydroformylation conditions. A multinuclear NMR spectroscopic investigation of the replacement reactions shows that [CpTi(μ3-S)3Rh3(CO)5(PPh3)] (4a), 4b, and 4c are intermediary species in the replacement reactions leading to 5, the decarbonylation of 4c being the key step for the observed stereoselectivity. The reaction of 3 with diphosphines gives the complexes [CpTi(μ3-S)3Rh3(μ-P−P)(CO)4] (P−P = 1,2-bis(diphenylphosphine)ethane (dppe); 1,3-bis(diphenylphosphine)propane, (dppp)), [CpTi(μ3-S)3Rh3(CO)4(η2-(R)-BINAP)], and [CpTi(μ3-S)3Rh3(μ-dppe)(CO)2(η2-dppe)], in which the heterotetranuclear metal framework is maintained.

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Syntheses, x-ray crystal structures, and fluxional behavior of the clusters Cp3Co3(.mu.2-CO)(.mu.3-CO)(.mu.-H)2, Cp3Co3(.mu.-H)(.mu.3-.eta.2-HC:NCMe3), and Cp*3Co3(.mu.2-H)(.mu.3-.eta.2-HC:NCMe2CH2Me)

Abstract: Behavior of the Clusters Cp3C<>3(/i2-CO)(/#3-CO)(^-H)2, Cp3Co3

Cited by 21 publications

References 2 publications

Synthesis of Triruthenium Complexes Containing a Triply Bridging Pyridyl Ligand and Its Transformations to Face-Capping Pyridine and Perpendicularly Coordinated Pyridyl Ligands

Synthesis of Triruthenium Complexes Containing a Triply Bridging Pyridyl Ligand and Its Transformations to Face-Capping Pyridine and Perpendicularly Coordinated Pyridyl Ligands

Synthesis of an Electron-Deficient Triruthenium Hydrido Complex Having a Bridging Carbonyl Ligand: Influence of a CO Ligand on the Properties and Reactivities of a Hydrido Cluster

Early−Late Heterotetranuclear Complexes (TiRh₃) with Bridging Sulfido Ligands: Ligand Replacement Reactions and Catalytic Activity in Hydroformylation of Olefins

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Syntheses, x-ray crystal structures, and fluxional behavior of the clusters Cp*3Co3(.mu.2-CO)(.mu.3-CO)(.mu.-H)2, Cp*3Co3(.mu.-H)(.mu.3-.eta.2-HC:NCMe3), and Cp*3Co3(.mu.2-H)(.mu.3-.eta.2-HC:NCMe2CH2Me)

Abstract: Behavior of the Clusters Cp*3C<>3(/i2-CO)(/#3-CO)(^-H)2, Cp*3Co3

Cited by 21 publications

References 2 publications

Synthesis of Triruthenium Complexes Containing a Triply Bridging Pyridyl Ligand and Its Transformations to Face-Capping Pyridine and Perpendicularly Coordinated Pyridyl Ligands

Synthesis of Triruthenium Complexes Containing a Triply Bridging Pyridyl Ligand and Its Transformations to Face-Capping Pyridine and Perpendicularly Coordinated Pyridyl Ligands

Synthesis of an Electron-Deficient Triruthenium Hydrido Complex Having a Bridging Carbonyl Ligand: Influence of a CO Ligand on the Properties and Reactivities of a Hydrido Cluster

Early−Late Heterotetranuclear Complexes (TiRh3) with Bridging Sulfido Ligands: Ligand Replacement Reactions and Catalytic Activity in Hydroformylation of Olefins

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Syntheses, x-ray crystal structures, and fluxional behavior of the clusters Cp3Co3(.mu.2-CO)(.mu.3-CO)(.mu.-H)2, Cp3Co3(.mu.-H)(.mu.3-.eta.2-HC:NCMe3), and Cp*3Co3(.mu.2-H)(.mu.3-.eta.2-HC:NCMe2CH2Me)

Abstract: Behavior of the Clusters Cp3C<>3(/i2-CO)(/#3-CO)(^-H)2, Cp3Co3

Early−Late Heterotetranuclear Complexes (TiRh₃) with Bridging Sulfido Ligands: Ligand Replacement Reactions and Catalytic Activity in Hydroformylation of Olefins