Synthesis and Characterization of New Square Planar Iridium Complexes [trans-Ir(CO)L2X] (L = PCy3, X = OH or OCH3; L = P(p-tolyl)3, X = OCH2C6H5 or O(p-C6H4CH3)): Crystal and Molecular Structures of trans-Ir(CO)(OH)(PCy3)2, trans-Ir(CO)(OCH2C6H5)(P(p-tolyl)3)2, and trans-Ir(CO)(O-p-C6H4CH3)(P(p-tolyl)3)2

Miller, Cynthia A.; Janik, Thomas S.; Lake, Charles H.; Toomey, Laurence M.; Atwood, Jim D.

doi:10.1021/om00024a059

Cited by 21 publications

(9 citation statements)

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“…Similarly, the lies within the expected range, and the IrÀO distance (2.09 ä) is comparable to the length of an IrÀO single bond. [33] Such tight ether coordination was previously observed in a similar Ir I complex. [34] The CÀN distance (1.29 ä) does not indicate any appreciable amount of metal±imine p backbonding.…”

Section: Syntheses Of Complexessupporting

confidence: 65%

Chiral Xyliphos Complexes for the Catalytic Imine Hydrogenation Leading to the Metolachlor Herbicide: Isolation of Catalyst–Substrate Adducts

Dorta

Broggini

Stoop³

et al. 2003

Chemistry A European J

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Iridium complexes relevant to the catalytic enantioselective hydrogenation of 2-methyl-6-ethylphenyl-1'-methyl-2'-methoxyethylimine (MEA-imine, 1) in the Syngenta Metolachlor (3) process were prepared and characterized. Reaction of the diphosphane (S)-1-[(R)-2-(diphenylphosphanyl)ferrocenyl]ethyldi(3,5-xylyl)phosphane ((S)-(R)-Xyliphos, (S)-(R)-4) with [Ir(2)(micro-Cl)(2)(cod)(2)] (cod=1,5-cyclooctadiene) afforded [Ir(Cl)(cod)[(S)-(R)-4]] (7), which reacted with AgBF(4) to form [Ir(cod)[(S)-(R)-4]]BF(4) (8). Complexes 7 and 8 reacted with iodide to yield [Ir(I)(cod)[(S)-(R)-4]] (9). When 9 was treated with one and two equivalents of HBF(4), two isomers of the cationic Ir(III) iodo hydrido complex [Ir(I)(H)(cod)[(S)-(R)-4]]BF(4) were solated (10 and 11, respectively). Complex 9 was oxidized with one equivalent of I(2) to give the iodo-bridged dinuclear species [Ir(2)I(2)(micro-I)(3)[(S)-(R)-4](2))]I (12). [Ir(2)(micro-Cl)(2)(coe)(4)] (coe=cyclooctene) reacted with (S)-(R)-4 to yield the chloro-bridged dinuclear complex [Ir(2)(micro-Cl)(2)[(S)-(R)-4](2)] (13). Complexes 7-12 were structurally characterized by single-crystal X-ray diffraction and tested as single-component catalyst precursors for enantioselective hydrogenation of MEA-imine. Complex 10 and dinuclear complex 12 gave the best catalytic results. Efforts were also directed at isolating substrate- or product-catalyst adducts: Treatment of 8 with 2,6-dimethylphenyl-1'-methyl-2'-methoxyethylimine (DMA-imine, 14, a model for 1) under H(2) allowed four isomers of [Ir(H)(2)[(S)-(R)-4](14)]BF(4) (18-21) to be isolated. These analytically pure isomers were fully characterized by 2D NMR techniques. X-ray structural analysis of an Ir(I)-imine adduct, namely, [Ir(C(2)H(4))(2)(14)]BF(4) (25), which was prepared by reacting [IrCl(C(2)H(4))(4)] with [Ag(14)(2)]BF(4) (16), confirmed the kappa(2) coordination mode of imine 14.

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Section: Syntheses Of Complexessupporting

confidence: 65%

Chiral Xyliphos Complexes for the Catalytic Imine Hydrogenation Leading to the Metolachlor Herbicide: Isolation of Catalyst–Substrate Adducts

Dorta

Broggini

Stoop³

et al. 2003

Chemistry A European J

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“…The reaction of Vaska's complex, trans -[Ir(CO)Cl(PR 3 ) 2 ] with NaOMe, followed by hydrolysis, gives rise to the Ir(I) complexes trans -[Ir(CO)(OH)(PR 3 ) 2 ] . The complexes can undergo phosphine exchange reactions.…”

Section: 3 Iridiummentioning

confidence: 99%

“…The hydroxy ligand can also play a spectator role, as seen in the phosphine ligand exchange reaction of trans -Ir(CO)(P( p -tolyl) 3 ) 2 OH with PCy 3 (PCy 3 = tricyclohexylphosphine) in benzene to produce trans -Ir(CO)(PCy 3 ) 2 OH . This exchange reaction has been used to produce a number of Vaska-type complexes with different phosphines; it works best when the incoming phosphine ligand is more electron-rich than the leaving phosphine moiety …”

Section: 3 Iridiummentioning

confidence: 99%

Organometallic Hydroxides of Transition Elements

et al. 2006

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“…The IrÀO bond length (2.102 (19) ) is quite short and comparable to the length of a single IrÀO bond. [9,15,16] The DMA-iridium chelate ring is slightly puckered (a comparison with the DMAamine analogue 19 is presented in Table 1), whereas the C(11) atom is perfectly coplanar with the C(12), C (13), and N atoms, thus precluding any significant charge delocalization from the metal into the p * orbital of the C=N double bond.…”

mentioning

confidence: 99%

Iridium–Imine and –Amine Complexes Relevant to the (S)‐Metolachlor Process: Structures, Exchange Kinetics, and CH Activation by Ir^I Causing Racemization

Dorta

Broggini

Kissner³

et al. 2004

Chemistry A European J

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Iridium complexes of DMA-imine [2,6-dimethylphenyl-1'-methyl-2'-methoxyethylimine, 1 a) and (R)-DMA-amine [(1'R)-2,6-dimethylphenyl-1'-methyl-2'-methoxyethylamine, 2 a] that are relevant to the catalytic imine hydrogenation step of the Syngenta (S)-Metolachlor process were synthesized: metathetical exchange of [Ir2Cl2(cod)2] (cod=1,5-cyclooctadiene) with [Ag(1 a)2]BF4 and [Ag((R)-2 a)2]BF4 afforded [Ir(cod)(kappa2- -1 a)]BF4 (11) and [Ir(cod)(kappa2-(R)-2 a)]BF4 ((R)-19)), respectively. These complexes were then used in stopped-flow experiments to study the displacement of amine 2 a from complex 19 by imine 1 a to form the imine complex 11, thus modeling the product/substrate exchange step in the catalytic cycle. The data suggest a two-step associative mechanism characterized by k1=(2.6+/-0.3) x 10(2) M(-1) s(-1) and k2=(4.3+/-0.6) x 10(-2) s(-1) with the respective activation energies EA1=(7.5+/-0.6) kJ mol(-1) and EA2=(37+/-3) kJ mol(-1). Furthermore, complex 11 reacted with H2O to afford the hydrolysis product [Ir(cod)(eta(6-)-2,6-dimethylaniline)]BF4 (12), and with I2 to liberate quantitatively the DMA-iminium salt 14. On the other hand, the chiral amine complex (R)-19 formed the optically inactive eta6-bound compound [Ir(cod)(eta6-rac-2 a)]BF4 (rac-18) upon dissolution in THF at room temperature, presumably via intramolecular C-H activation. This racemization was found to be a two-step event with k'1=9.0 x 10(-4) s(-1) and k2=2.89 x 10(-5) s(-1), featuring an optically active intermediate prior to sp3 C-H activation. Compounds 11, 12, rac-18, and (R)-19 were structurally characterized by single-crystal X-ray analyses.

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Cited by 21 publications

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Chiral Xyliphos Complexes for the Catalytic Imine Hydrogenation Leading to the Metolachlor Herbicide: Isolation of Catalyst–Substrate Adducts

Chiral Xyliphos Complexes for the Catalytic Imine Hydrogenation Leading to the Metolachlor Herbicide: Isolation of Catalyst–Substrate Adducts

Organometallic Hydroxides of Transition Elements

Iridium–Imine and –Amine Complexes Relevant to the (S)‐Metolachlor Process: Structures, Exchange Kinetics, and CH Activation by Ir^I Causing Racemization

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Cited by 21 publications

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Chiral Xyliphos Complexes for the Catalytic Imine Hydrogenation Leading to the Metolachlor Herbicide: Isolation of Catalyst–Substrate Adducts

Chiral Xyliphos Complexes for the Catalytic Imine Hydrogenation Leading to the Metolachlor Herbicide: Isolation of Catalyst–Substrate Adducts

Organometallic Hydroxides of Transition Elements

Iridium–Imine and –Amine Complexes Relevant to the (S)‐Metolachlor Process: Structures, Exchange Kinetics, and CH Activation by IrI Causing Racemization

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Iridium–Imine and –Amine Complexes Relevant to the (S)‐Metolachlor Process: Structures, Exchange Kinetics, and CH Activation by Ir^I Causing Racemization