The Molecular Structure of [Os3Rh4(μ3‐η1:η1:η1‐C6H5CH3)(CO)13]: A Face‐Capping Bonding Mode for Arenes in Organometallic Clusters

Lau, Jasmine Po-Kwan; Yang, Lin; Wong, Wing Tak

doi:10.1002/ange.200250519

Cited by 6 publications

(6 citation statements)

References 21 publications

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“…The C À C lengths (1.416(4)-1.435(4) ) of the m 3 -benzene ligand in 1-py are slightly longer than those of free benzene, where a reduced bond length alternation was retained. [15,16] Such trend of CÀC lengths in the m 3 -benzene ligand is comparable to that predicted for the m 3 -benzene adsorbed on a Pd(111) surface. [8] The planar COT ligand supported the Pd 3 triangle at the backside through m 3 -h 3 :h 3 :h 2 -coordination mode.…”

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confidence: 73%

“…[15,16] The exchange of the m 3 -benzene ligand in 1-CH 3 CN with free arenes took place at 80 8C in CD 3 NO 2 with [D 6 ]benzene, toluene, p-xylene, mesitylene, tert-butylbenzene, anisole, and methylbenzoate representing substrates (Scheme 5). [22] The equilibrium constant K eq for each substituted benzene was smaller than 1, indicating that steric effects contributed to the thermodynamic stability of m 3 -arene Pd 3 complexes.…”

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confidence: 99%

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Modulation of Benzene or Naphthalene Binding to Palladium Cluster Sites by the Backside‐Ligand Effect

et al. 2015

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The backside-ligand modulation strategy to enhance the substrate binding property of Pd clusters is reported. The benzene or naphthalene binding ability of Pd 3 or Pd 4 clusters is enhanced significantly by the backside cyclooctatetraene ligand, leading to the formation of the first solution-stable benzene-or naphthalene Pd clusters. The present results imply that the ligand design of the metal clusters, especially for the backside ligand of the metal cluster site, is crucial to acquire a desired reactivity of metal clusters.Much attention has been focused on the roles of metal clusters in catalysis. It is of particular interest to explore the substrate binding and activation modes at the bridging coordination sites of metal clusters, as multiple metal atoms of a metal cluster site may facilitate some elementary reactions in catalytic cycles, or bring new modes of substrate binding and transformation.[1] Despite the importance of palladium in catalysis, however, the way that Pd clusters bind substrates at their m n -bridging coordination sites (n ! 3) has not been extensively investigated and thus poorly characterized.[2] This is mainly due to the difficulty to generate reactive molecular Pd clusters in homogeneous systems.[3] To overcome this problem, it is necessary to develop a ligand system which not only supports a Pd cluster core, but also bring a suitable environment for substrate binding at a Pd cluster site through electronic and/or steric effects. In designing the ligand systems for reactive Pd clusters, we focused on the roles of the backside auxiliary ligand, as the property of a metal cluster site may be largely affected by electronic effects of the backside ligand, in view of the well-established trans influence and trans effect in the mononuclear metal systems (Scheme 1).[4] Herein, we report that the backside carbocyclic ligands have a large effect on the substrate binding property at a Pd 3 cluster site, through demonstration of the significantly enhanced benzene binding ability of a Pd 3 cluster as compared to known Pd complexes. Furthermore, it was also confirmed that the backside-ligand-modulation strategy can be applied to the naphthalene binding at a m 4 -Pd 4 cluster site. We chose benzene as the target substrate in examining the backside-ligand effect on the substrate binding at a m 3 -Pd 3 cluster site, as benzene is one of the weakest coordinating substrates in organopalladium chemistry. In fact, mononuclear Pd complexes that bind benzene stably in solution have not been reported. [5,6] The lack of solution-stable benzene-Pd complexes would have raised a question on the involvement of benzene-Pd p-adducts in Pd-catalyzed benzene transformations.[7] The m 3 -benzene coordination to molecular Pd clusters is unprecedented, while the potential ability of Pd clusters to bind benzene may be indicated by the Pd surface chemistry; that is, it has been proposed that adsorbed benzene on Pd surface adopts m 3 -or m 4 -bridging coordination modes. [8] Our laboratory recently addressed the ...

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confidence: 99%

Modulation of Benzene or Naphthalene Binding to Palladium Cluster Sites by the Backside‐Ligand Effect

et al. 2015

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“…Deeming and co-workers [18] were the first to demonstrate the reactivity of organometallic clusters with 2-vinylpyridine in which they showed that [Os 3 (CO) 10 (l-H) 2 ] and [Os 3 (CO) 10 -(MeCN) 2 ] react with 2-vinylpyridine with C-H bond cleavage at the vinyl carbon atom to give the triosmium cluster [Os 3 (CO) 10 (g 1 :g 2 :g 1 -NC 5 H 4 CH@CH)(l-H)] with an open structure. A similar bonding mode of NC 5 H 4 CH@CH has been reported in [Os 6 (CO) 20 (l-g 1 :g 2 :g 1 -NC 5 H 4 CH@ CH)(l-H)] [19], [Os 4 Rh(CO) 13 (l-g 1 :g 2 :g 1 -NC 5 H 4 CH@ CH)(l-H) 4 ] [20] and in the mononuclear carbonyl complex [Re(NC 5 H 4 CH@CH)(CO) 4 ] [21]. In contrast with the rich 2-vinylpyridine chemistry with most of the transition metals, noted above, morpholine has far less been investigated except for our recent report on the reaction of [Os 3 (CO) 10 -(MeCN) 2 ] to afford the C-H oxidative-addition product [Os 3 (CO) 10 (l-g 2 -NC 4 H 6 O)(l-H)] [22].…”

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confidence: 51%

“…The Re-Re bond distance of 3.0331(3) Å clearly corresponds to a single bond which is in accordance with the 18-electron count for each metal. This bond length is comparable to the Re-Re bond distance of 3.three equatorial CO ligands bonded to Re(1) have torsion angles of the order 81(1)°to 155(4)°with respect to Re(2)-C(8) which is typical of [M 2 (CO) 10Àx L x ] compounds[29].The nitrogen atom of 2-vinylpyridine ligand is axially coordinated to Re(1) and the Re-N bond length of 2.208(4) Å is comparable to the Re-N bond distances of 2 20…”

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confidence: 94%

Dirhenium carbonyl complexes bearing 2-vinylpyridine, morpholine and 1-methylimidazole ligands

Kabir

Ahmed

Das

et al. 2008

Journal of Organometallic Chemistry

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Treatment of the labile compound [Re 2 (CO) 8 (MeCN) 2 ] with 2-vinylpyridine in refluxing benzene affords exclusively the new compound [Re 2 (CO) 8 (l-g 1 :g 2 -NC 5 H 4 CH@CH 2 )] (1) in 39% yield in which the l-g 1 :g 2 -vinylpyridine ligand is coordinated to one Re atom through the nitrogen and to the other Re atom via the olefinic double bond. Reaction of [Re 2 (CO) 8 (MeCN) 2 ] with morpholine in refluxing benzene furnishes two compounds, [Re 2 (CO) 9 (g 1 -NC 4 H 9 O)] (2) and [Re 2 (CO) 8 (g 1 -NC 4 H 9 O) 2 ] (3) in 5% and 29% yields, respectively. Reaction of [Re 2 (CO) 8 (MeCN) 2 ] with 1-methylimidazole gives [Re 2 (CO) 8 {g 1 -NC 3 H 3 N(CH 3 )} 2 ] (4) and the mononuclear compound fac-[ReCl(CO) 3 {g 1 -NC 3 H 3 N(CH 3 )} 2 ] (5) in 18% and 26% yields, respectively. In the disubstituted compounds 2 and 4, the heterocyclic ligands occupy equatorial coordination sites. The mononuclear compound 5 consists of three CO groups, two N coordinated g 1 -1-methylimidazole ligands and a terminal Cl ligand. The XRD structures of complexes 1, 3 and 5 are reported.

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Modulation of Benzene or Naphthalene Binding to Palladium Cluster Sites by the Backside‐Ligand Effect

et al. 2015

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The Molecular Structure of [Os₃Rh₄(μ₃‐η¹:η¹:η¹‐C₆H₅CH₃)(CO)₁₃]: A Face‐Capping Bonding Mode for Arenes in Organometallic Clusters

Cited by 6 publications

References 21 publications

Modulation of Benzene or Naphthalene Binding to Palladium Cluster Sites by the Backside‐Ligand Effect

Modulation of Benzene or Naphthalene Binding to Palladium Cluster Sites by the Backside‐Ligand Effect

Dirhenium carbonyl complexes bearing 2-vinylpyridine, morpholine and 1-methylimidazole ligands

Modulation of Benzene or Naphthalene Binding to Palladium Cluster Sites by the Backside‐Ligand Effect

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