Binuclear Oxidative Addition of Hydrogen in Diamidonaphthalene-Bridged Diiridium Complexes

Jiménez, M. Victoria; Sola, Eduardo; López, José A.; Lahoz, Fernando J.; Oro, Luis A.

doi:10.1002/(sici)1521-3765(19980807)4:8<1398::aid-chem1398>3.3.co;2-r

Cited by 16 publications

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“…The 31 P{ 1 H} NMR resonance of 2- d 2 also exhibits a Δδ of 0.12 ppm with respect to that of 2- d . We note that similar deuterium isotopic shifts have been reported for other iridium hydrido derivatives as well. 15a, …”

Section: Resultssupporting

confidence: 86%

Labile Hydrido Complexes of Iridium(III): Synthesis, Dynamic Behavior in Solution, and Reactivity toward Alkenes

et al. 1999

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The trisacetonitrile complexes [IrClH(PiPr3)(NCCH3)3]BF4 (1) and [IrH2(PiPr3)(NCCH3)3]BF4 (2) have been prepared in one-pot reactions with high yields by reaction of the iridium(I) dimers [Ir(μ-Cl)(coe)2]2 and [Ir(μ-OMe)(cod)2]2 with the phosphonium salt [HPiPr3]BF4. The rates of exchange between free acetonitrile and the labile acetonitrile ligands of complexes 1 and 2 have been measured by NMR spectroscopy. This kinetic study has shown that both complexes readily dissociate one acetonitrile ligand trans to hydride, giving rise to fluxional five-coordinate intermediates. Substitution products 3−7 have been obtained by treatment of complexes 1 and 2 with CO and PMe3. The structures determined for 3−7 can be rationalized on the basis of the steric requirements of the ligands, indicating that the products are formed by thermodynamic control. Ethene inserts reversibly into the Ir−H bond of 1 to give the compound [IrCl(Et)(PiPr3)(NCCH3)3]BF4 (8), which has been used for the preparation of the stable ethyliridium(III) complexes [IrCl(Et)(PiPr3)(Py)2(NCCH3)]BF4 (9) and [Ir(η2-O2CCH3)Cl(Et)(PiPr3)(NCCH3)3] (10), respectively. The molecular structure of 10 has been determined by X-ray crystallography. The reaction of 2 with ethene, at low temperature, results in the sequential formation of the ethene complex [IrH2(η2-C2H4)(PiPr3)(NCCH3)2]BF4 (11) and the diethyl derivative [Ir(Et)2(PiPr3)(NCCH3)3]BF4 (14). At room temperature in solution, 14 undergoes reductive elimination of ethane to form the iridium(I) species [Ir(PiPr3)(NCCH3)3]BF4 (15) and [Ir(PiPr3)(η2-C2H4)(NCCH3)2]BF4 (16). These cations readily react with H2 to regenerate 2, closing a cycle for ethene hydrogenation in which several participating species have been identified. The reaction of 2 with propene in solution also allows the characterization of products of propene coordination (17) and insertion (18). In this case, the species obtained after elimination of propane are products of allylic C−H activation: [IrH(η3-C3H5)(PiPr3)(NCCH3)2]BF4 (19) and [IrH(η3-C3H5)(η2-C3H6)(PiPr3)(NCCH3)]BF4 (20). The structure of complex 19 has been determined by X-ray diffraction, and the kinetics of dissociation of its two labile acetonitrile ligands have been studied by NMR spectroscopy. Complex 19 undergoes electrophilic activation of H2 to give propene and reform the starting complex 2.

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Section: Resultssupporting

confidence: 86%

Labile Hydrido Complexes of Iridium(III): Synthesis, Dynamic Behavior in Solution, and Reactivity toward Alkenes

et al. 1999

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“…The 31 P{ 1 H} spectrum contains two singlets at δ 23.90 and 23.76, which split into two doublets due to the coupling of the hydride under off-resonance conditions, indicating that each iridium center coordinates one hydride ligand. The signals in the 13 C{ 1 H} spectrum corresponding to the C 1 and C 8 carbons of the diamidonaphthalene bridge are both doublets, at δ 154.56 ( J CP = 3.6 Hz) and 157.05 ( J CP = 2.8 Hz), indicating a transoid arrangement of the phosphine ligands in the dinuclear framework . The α-carbon of the alkynyl ligand appears as a doublet at δ 53.71 with a C−P coupling constant of 10.0 Hz, whereas the β-carbon appears as a singlet at δ 128.63.…”

Section: Resultsmentioning

confidence: 99%

“…The second signal, which is coupled to both phosphorus atoms with rather small coupling constants, can be assigned to a bridging hydride. The magnitude of the coupling constant between the bridging and the terminal hydrides ( J HH = 8.7 Hz) suggests a trans arrangement of these two ligands. , In the 13 C{ 1 H} NMR spectrum, the alkynyl ligand of 5 gives rise to a doublet at δ 68.36 ( J CP = 10.6 Hz) and a singlet at δ 103.90. Under off-resonance conditions, the doublet corresponding to the α-carbon splits into a doublet of doublets, showing a large J CH coupling of 19.9 Hz, in agreement with a trans disposition of the terminal alkynyl and the bridging hydride.…”

Section: Resultsmentioning

confidence: 99%

“…Despite the inertness of 1 in these additions, we have recently found that its oxidized derivatives [Ir 2 (μ-1,8-(NH) 2 naphth)H(CO) 2 (PiPr 3 ) 2 ](CF 3 SO 3 ) ( 2 ) and [Ir 2 (μ-1,8-(NH) 2 naphth)(CF 3 SO 3 ) 2 (CO) 2 (PiPr 3 ) 2 ] ( 3 ) (Scheme ) readily activate hydrogen . Again, this is in contrast with the behavior of mononuclear complexes, where the ability to undergo oxidative addition is enhanced by increasing the electron density at the metal center …”

Section: Introductionmentioning

confidence: 95%

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Competitive Reaction Pathways in the Addition of Phenylacetylene to Diamidonaphthalene-Bridged Diiridium Complexes

et al. 1999

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The oxidative addition of phenylacetylene to the monohydrido diiridium complex [Ir2(μ-1,8-(NH)2naphth)H(CO)2(PiPr3)2](CF3SO3) (2) and the diiridium(II) species [Ir2(μ-1,8-(NH)2naphth)(CF3SO3)2(CO)2(PiPr3)2] (3) has been studied. The kinetic product of the addition to 2 is the dihydridoalkynyl complex [Ir2(μ-1,8-(NH)2naphth)(μ-C⋮CPh)H2(CO)2(PiPr3)2](CF3SO3) (4), in which the alkynyl ligand bridges the iridium atoms in a μ,η1:η2-coordination mode. Compound 4 isomerizes in acetone solution to give the hydride-bridged complex [Ir2(μ-1,8-(NH)2naphth)(μ-H)H(C⋮CPh)(CO)2(PiPr3)2](CF3SO3) (5), in which both the alkynyl and the terminal hydride ligands are in a trans position with respect to the bridging hydride. The reaction of phenylacetylene with 3 gives different kinetic products depending on the solvent used. In CH2Cl2, the diiridium(III) derivative [Ir2(μ-1,8-(NH)2naphth)H(C⋮CPh)(CO)2(PiPr3)2](CF3SO3)2 (6) is obtained. On heating these CH2Cl2 solutions, 6 isomerizes into the vinylidene-bridged complex [Ir2(μ-1,8-(NH)2naphth)(μ-CCHPh)(CF3SO3)2(CO)2(PiPr3)2](7), which has been characterized by X-ray diffraction. The triflate ligands of 7 can be substituted by acetonitrile ligands to give the dicationic compound [Ir2(μ-1,8-(NH)2naphth)(μ-CCHPh)(NCCH3)2(CO)2(PiPr3)2](CF3SO3)2 (8). With acetone as the reaction solvent, the addition of phenylacetylene to 3 affords deprotonated compounds of formula [Ir2(μ-1,8-(NH)2naphth)(C⋮CPh)(CO)2(PiPr3)2](CF3SO3) (9 and 10). The thermally stable isomer 10 can be protonated to give 7 but can also react with an excess of phenylacetylene to give the neutral diiridium(II) species [Ir2(μ-1,8-(NH)2naphth)(C⋮CPh)2(CO)2(PiPr3)2] (11), which is the isolable product of the reaction of 3 with an excess of phenylacetylene in acetone. When this latter reaction is carried out in acetone/H2O as solvent, the acylalkynyl diiridium(II) complex [Ir2(μ-1,8-(NH)2naphth)(C⋮CPh)(C(O)CH2Ph)(CO)2(PiPr3)2] (12) is the major reaction product. The molecular structure of 12 was determined by X-ray diffraction.

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“…Use of chelating amine ligands provides amido-and imidobridged dinuclear complexes more resistant to the M-N bond cleavage 23 as in many mononuclear metal/NH bifunctional catalysts. 1,2,5, 7 Oro and co-workers synthesized the diamidobridged Rh II 2 complex 11 through dinuclear oxidative addition of I 2 to the Rh I 2 amido complex [{Rh(CO)(PPh 3 )} 2 {m-(NH) 2 C 10 H 6 }] as early as 1984.…”

Section: Amido-and Imido-bridged Dinuclear Complexesmentioning

confidence: 99%

Quest for metal/NH bifunctional bioinspired catalysis in a dinuclear platform

Kuwata

Ikariya

2010

Dalton Trans.

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Bifunctional catalysts, in which two functionalities cooperate in substrate activation and transformation, promote a number of chemical and biological reactions quite efficiently. This perspective mainly describes our efforts to extend the concept of the metal/NH bifunctional mononuclear catalysts to dinuclear systems. The late transition metal dinuclear complexes with bridging sulfonylated nitrogen donors and parent amides (NH(2)) are focused on particularly, while the chemistry of related nitrogen-bridged polynuclear complexes is also mentioned.

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Binuclear Oxidative Addition of Hydrogen in Diamidonaphthalene-Bridged Diiridium Complexes

Cited by 16 publications

References 0 publications

Labile Hydrido Complexes of Iridium(III): Synthesis, Dynamic Behavior in Solution, and Reactivity toward Alkenes

Labile Hydrido Complexes of Iridium(III): Synthesis, Dynamic Behavior in Solution, and Reactivity toward Alkenes

Competitive Reaction Pathways in the Addition of Phenylacetylene to Diamidonaphthalene-Bridged Diiridium Complexes

Quest for metal/NH bifunctional bioinspired catalysis in a dinuclear platform

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