Cp*Fe(Me2PCH2CH2PMe2)(CHO): Hydride shuttle reactivity of a thermally stable formyl complex

Sapsford, Joshua S.; Gates, Sarah J.; Doyle, Laurence R.; Taylor, Russell A.; Díez‐González, Silvia; Ashley, Andrew E.

doi:10.1016/j.ica.2019.01.022

Cited by 9 publications

(10 citation statements)

References 28 publications

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“…Similar tautomeric equilibria (between L(M–H) and (L–H)M) have now been reported for a variety of ligands (L) including Cp*, − indenide, dimethylglyoxime, − and diketiminate . Tautomeric equilibria might thus be viewed as a potential design feature in any catalytic cycle involving metal hydride intermediates.…”

Section: Introductionsupporting

confidence: 63%

Metal/Ligand Proton Tautomerism Facilitates Dinuclear H₂Reductive Elimination

Kuo

Goldberg

2020

J. Am. Chem. Soc.

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Using the doubly protic bis-pyrazole-pyridine ligand (N(NNH)2), we have synthesized an octahedral IrIII–H [HIr(κ3-N(NNH)(NN–))(CO)( t BuPy)]+ ([1-MH]+) from an IrI starting material. This hydride was generated by adding sufficient electron density to the metal center such that it became the thermodynamically preferred site of protonation. It was observed via UV–vis spectroscopy that [1-MH]+ establishes a [ t BuPy] dependent equilibrium with a ligand protonated square-planar IrI [Ir(N(NNH)2)(CO)]+ ([2-LH]+). This example of metal/ligand proton tautomerism is unusual in that the position of the equilibrium can be controlled by the concentration of exogeneous ligand (i.e., t BuPy). This equilibrium was shown to be key to the reactivity of the IrIII–H; 2 equiv of [1-MH]+ release H2, converting to the IrII dimer [[Ir(N(NN–)(NNH))(CO)( t BuPy)]2]2+ ([7]2+) under mild conditions (observable at room temperature). Mechanistic evidence is presented to support that this dinuclear reductive elimination occurs by tautomerization of the metal hydride [1-MH]+ to a ligand protonated species [1-LH]+, from which ligand dissociation is facile, generating [2-LH]+. Subsequent reaction of [2-LH]+ with [1-MH]+ allows for production of H2 and the IrII dimer [7]2+. The tautomerization between the metal-hydride and the ligand protonated species provides a low energy pathway for ligand dissociation, opening the needed coordination site. The ability to control the interconversion between a metal-hydride and a ligand-protonated congener using an exogeneous ligand introduces a new strategy for catalyst design with proton responsive ligands.

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Section: Introductionsupporting

confidence: 63%

Metal/Ligand Proton Tautomerism Facilitates Dinuclear H₂Reductive Elimination

Kuo

Goldberg

2020

J. Am. Chem. Soc.

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“…It has been previously suggest that transition metal formyl complexes can be stabilised by inclusion of a sterically demanding ligand, commonly a bulky phosphine. 3,4,33,47,48 The half-life for complex 3a (t1/2 = 2 h), was identical in C6D6 and THF solvent and did not change when running the reaction under 1 atm. of CO.…”

Section: Introductionmentioning

confidence: 91%

“…Increased oxycarbene character is expected to increase the metal ligand binding energy and therefore impact the position of the equilibrium between the metal formyl and metal hydrido carbonyl. [33][34][35][36] In this study, we document the preparation, structural characterisation, and bonding analysis (NBO, ETS-NOCV, QTAIM) of the first complete series of transition metal formyl complexes (M = Cr, Mn, Fe, Co, Rh, W, and Ir). This includes unprecedented examples of crystallographically characterised Cr, Co and Ir formyl complexes.…”

Section: Introductionmentioning

confidence: 99%

Magnesium-Stabilised Transition Metal Formyl Complexes: Structures, Bonding, and Ethenediolate Formation

Parr

White

Crimmin

2021

Preprint

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Herein we report the first comprehensive series of crystallographically characterised transition metal formyl complexes. In these complexes, the formyl ligand is trapped as part of a chelating structure between a transition metal (Cr, Mn, Fe, Co, Rh, W, and Ir) and a magnesium (Mg) cation. Calculations suggest that this bonding mode results in significant oxycarbene-character of the formyl ligand. Electron-rich late-transition metal complexes have the highest oxycarbene-character to the bonding and are the most stable in solution. Further reaction of a heterometallic Cr---Mg formyl complex results in a rare example of C–C coupling and formation of an ethenediolate complex. These results show that well-defined transition metal formyl complexes are potential intermediates in the homologation of carbon monoxide.

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“…This then, in turn, should bias the position of the equilibrium toward the metal formyl species rather than the metal hydrido carbonyl complex. [30][31][32][33] A survey of the Cambridge Crystallographic Data Centre (CCDC) database reveals that despite nearly 50 years of research into transition metal formyl complexes, only a modest number have been structurally characterised (supporting information, Fig. S11 and Table S2 †).…”

Section: Introductionmentioning

confidence: 99%

“…This then, in turn, should bias the position of the equilibrium toward the metal formyl species rather than the metal hydrido carbonyl complex. 30–33…”

Section: Introductionmentioning

confidence: 99%

Magnesium-stabilised transition metal formyl complexes: structures, bonding, and ethenediolate formation

2022

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Cp*Fe(Me2PCH2CH2PMe2)(CHO): Hydride shuttle reactivity of a thermally stable formyl complex

Abstract: psfordD toshu F nd qtesD rh tF nd hoyleD vurene F nd ylorD ussell eF nd h¡ %ezEqonz¡ lezD ilvi nd eshleyD endrew iF @PHIWA 9gpBpe@wePgrPgrPwePA@gryA X hydride shuttle retivity of thermlly stle formyl omplexF9D snorgni himi tFD RVV F ppF PHIEPHUF

Cited by 9 publications

References 28 publications

Metal/Ligand Proton Tautomerism Facilitates Dinuclear H₂Reductive Elimination

Metal/Ligand Proton Tautomerism Facilitates Dinuclear H₂Reductive Elimination

Magnesium-Stabilised Transition Metal Formyl Complexes: Structures, Bonding, and Ethenediolate Formation

Magnesium-stabilised transition metal formyl complexes: structures, bonding, and ethenediolate formation

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Cp*Fe(Me2PCH2CH2PMe2)(CHO): Hydride shuttle reactivity of a thermally stable formyl complex

Abstract: psfordD toshu F nd qtesD rh tF nd hoyleD vurene F nd ylorD ussell eF nd h¡ %ezEqonz¡ lezD ilvi nd eshleyD endrew iF @PHIWA 9gpBpe@wePgrPgrPwePA@gryA X hydride shuttle retivity of thermlly stle formyl omplexF9D snorgni himi tFD RVV F ppF PHIEPHUF

Cited by 9 publications

References 28 publications

Metal/Ligand Proton Tautomerism Facilitates Dinuclear H2Reductive Elimination

Metal/Ligand Proton Tautomerism Facilitates Dinuclear H2Reductive Elimination

Magnesium-Stabilised Transition Metal Formyl Complexes: Structures, Bonding, and Ethenediolate Formation

Magnesium-stabilised transition metal formyl complexes: structures, bonding, and ethenediolate formation

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Metal/Ligand Proton Tautomerism Facilitates Dinuclear H₂Reductive Elimination

Metal/Ligand Proton Tautomerism Facilitates Dinuclear H₂Reductive Elimination