Terminal and Bridging Parent Amido 1,5‐Cyclooctadiene Complexes of Rhodium and Iridium

Mena, Inmaculada; Jaseer, E. A.; Garcı́a-Orduña, Pilar; Lahoz, Fernando J.; Oro, Luis A.

doi:10.1002/chem.201204391

Cited by 29 publications

(14 citation statements)

References 96 publications

(74 reference statements)

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“…In the presence of PMe 3 the trinuclear entity fragments into mononuclear pentacoordinated species [Ir(tfbb)(PMe 3 ) 2 (NH 2 )] (1-A) with trigonal bipyramidal geometry in an exothermic process (70.3 kcal mol À1 ). [21] The intermediate 1-A bears a highly nucleophilic terminal amido moiety located at an axial site, trans to one of the olefinic bond. The migratory insertion of olefins into metal-amido bonds through a fourcenter transition state has been shown to be an efficient mechanism for the formation of carbon-nitrogen bonds.…”

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confidence: 99%

CNH₂ Bond Formation Mediated by Iridium Complexes

et al. 2014

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In the presence of phosphanes (PR3 ), the amido-bridged trinuclear complex [{Ir(μ-NH2 )(tfbb)}3 ] (tfbb=tetrafluorobenzobarrelene) transforms into mononuclear discrete compounds [Ir(1,2-η(2) -4-κ-C12 H8 F4 N)(PR3 )3 ], which are the products of the CN coupling between the amido moiety and a vinylic carbon of the diolefin. An alternative synthetic approach to these species involves the reaction of the 18 e(-) complex [Ir(Cl)(tfbb)(PMePh2 )2 ] with gaseous ammonia and additional phosphane. DFT studies show that both transformations occur through nucleophilic attack. In the first case the amido moiety attacks a diolefin coordinated to a neighboring molecule following a bimolecular mechanism induced by the highly basic NH2 moiety; the second pathway involves a direct nucleophilic attack of ammonia to a coordinated tfbb molecule.

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CNH₂ Bond Formation Mediated by Iridium Complexes

et al. 2014

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“…The Cp* ligands arrange in am utually cis orientation, andapseudo C2 symmetric axis lies perpendicular to the Ir 2 N 2 core. The absence of metalmetal bonding interactions is confirmed by aI r ÀIr distance of 3.3079 (5) ,w hichi sl ongert han those of the reported amidobridged Ir I complexes, for example, 2.8146(3) and 2.9577 (4) in [Ir(m 2 -NH 2 )L 2 ] 2 (L 2 = cod and (CO) 2 ); [13] 2.837 (meanv alue) in an amido/imido-bridged Ir III complex, [14] [Cp*Ir(m 2 -NHTs)(m 2 -NTs)IrCp*][OTf] (Ts = SO 2 C 6 H 4 CH 3 ,T f= SO 2 CF 3 ); and 2.584(1) in ab is(amido)-bridged Ir II complex, [15] [Cp*Ir{(m 2 -NH) 2 C 10 H 6 -1,8}IrCp*]. The IrÀNb ond lengths (2.127 ,m ean value)o f3a' are distinct from that of the reportedm onomeric amidoiridium complex, Cp*Ir[k 2 (N,C)-(NHC(C 6 H 5 ) 2 -2-C 6 H 4 )] (1.903(2) ), [4] and are closer to the Ir-sulfonylamido bonds in [Cp*Ir(m 2 -NHTs)(m 2 -NTs)IrCp*][OTf] (2.114(6) and 2.131(6) )o rt ot he Ir-arylamido bonds in [Cp*Ir{(m 2 -NH) 2 C 10 H 6 -1,8}IrCp*] (2.02-2.11 ).…”

Section: Synthesis Of Amidoiridiumcomplexes By Deprotonation Of Aminementioning

confidence: 70%

Comparative Study of Bifunctional Mononuclear and Dinuclear Amidoiridium Complexes with Chiral C−N Chelating Ligands for the Asymmetric Transfer Hydrogenation of Ketones

Sato

Kayaki

Ikariya

2016

Chemistry An Asian Journal

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A series of new bifunctional C-N chelating Ir complexes possessing a metal/NH group was synthesized by cyclometalation of optically active primary benzylic amines such as O-silylated (S)-2-amino-2-phenylethanols (1 a and 1 a'), (R)-5-amino-6,7,8,9-tetrahydro-5H-benzocycloheptene (1 b), and (R)-1-phenyl-2,2-dimethylpropylamine (1 c). Although treatment of KOtBu with the amine complexes originating from 1 a and 1 a' afforded amido-bridged dinuclear complexes (3 a and 3 a'), more sterically hindered complexes were solely transformed into the coordinatively unsaturated mononuclear amido complexes (3 b and 3 c), which can serve as real catalyst species in the asymmetric transfer hydrogenation. The structural difference in the C-N chelate framework markedly affected the catalytic performance. Among them, amido complex 3 c showed a pronounced ability to catalyze the transfer hydrogenation of acetophenone in 2-propanol, even at a low temperature of -30 °C. A hydridoiridium complex (4 c) was also identified in the reaction of 3 c in 2-propanol, which provides mechanistic insights into the enantiodiscriminating step in the hydrogen transfer to prochiral ketones.

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“…The mechanism of the formation of 2 – 4 from 1 and phosphanes has been studied in detail by DFT calculations, using PMe 3 as model for the phosphane ligands. In the presence of PMe 3 the trinuclear entity fragments into mononuclear pentacoordinated species [Ir(tfbb)(PMe 3 ) 2 (NH 2 )] ( 1 ‐ A ) with trigonal bipyramidal geometry in an exothermic process (70.3 kcal mol −1 ) 21. The intermediate 1 ‐ A bears a highly nucleophilic terminal amido moiety located at an axial site, trans to one of the olefinic bond.…”

Section: Methodsmentioning

confidence: 99%