Oxygen Atom “Cut and Paste” from Carbon Dioxide to a Fischer Carbene Complex

Boom, Milko E. van der

doi:10.1002/anie.200803953

Cited by 16 publications

(2 citation statements)

References 43 publications

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“…On the other hand, the reactivity is slightly reminiscent of what is observed in f-element chemistry, ,− in particular with the formation of an intermediate where CO 2 is inserted between Ir and Al, but the protonation of CO 2 and the formation of a terminal hydroxyl unit are unique. Conceptually, the chemistry observed here is related to the heteroallene dipolar addition chemistry in Fisher carbene, − silylene, − or boryl complexes, for instance in the case where CO 2 is added across a IrC(H)(OR) fragment, which is nucleophilic at Ir and electrophilic at C, leading to an iridium carbonyl adduct and HC(O)OR …”

Section: Resultsmentioning

confidence: 99%

Strongly Polarized Iridium^δ−–Aluminum^δ+ Pairs: Unconventional Reactivity Patterns Including CO₂ Cooperative Reductive Cleavage

et al. 2021

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The iridium tetrahydride complex Cp*IrH4 reacts with a range of isobutylaluminum derivatives of general formula Al(iBu) x (OAr)3–x (x = 1, 2) to give the unusual iridium aluminum species [Cp*IrH3Al(iBu)(OAr)] (1) via a reductive elimination route. The Lewis acidity of the Al atom in complex 1 is confirmed by the coordination of pyridine, leading to the adduct [Cp*IrH3Al( i Bu)(OAr)(Py)] (2). Spectroscopic, crystallographic, and computational data support the description of these heterobimetallic complexes 1 and 2 as featuring strongly polarized Al(III)δ+–Ir(III)δ− interactions. Reactivity studies demonstrate that the binding of a Lewis base to Al does not quench the reactivity of the Ir–Al motif and that both species 1 and 2 promote the cooperative reductive cleavage of a range of heteroallenes. Specifically, complex 2 promotes the decarbonylation of CO2 and AdNCO, leading to CO (trapped as Cp*IrH2(CO)) and the alkylaluminum oxo ([(iBu)(OAr)Al(Py)]2(μ-O) (3)) and ureate ({Al(OAr)( i Bu)[κ2-(N,O)AdNC(O)NHAd]} (4)) species, respectively. The bridged amidinate species Cp*IrH2(μ-CyNC(H)NCy)Al( i Bu)(OAr) (5) is formed in the reaction of 2 with dicyclohexylcarbodiimine. Mechanistic investigations via DFT support cooperative heterobimetallic bond activation processes.

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Section: Resultsmentioning

confidence: 99%

Strongly Polarized Iridium^δ−–Aluminum^δ+ Pairs: Unconventional Reactivity Patterns Including CO₂ Cooperative Reductive Cleavage

et al. 2021

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“…The initial discovery was somewhat fortuitous, in that CO 2 was chosen as an electrophilic C 1 synthon that also displays a rich coordination chemistry, including several examples with iridium(I) . Exposure of carbene 8 to an atmosphere of CO 2 led to quantitative generation of the carbonyl adduct (PNP)Ir−CO ( 13 ) with expulsion of tert -butyl formate (eq ), a remarkable and unusual example of direct oxygen-atom abstraction from CO 2 . , In light of previous results from Mayer’s laboratory regarding the oxidative addition of CO 2 and other heterocumulenes, we hypothesized that formation of the stable iridium carbonyl complex might also provide driving force for the decarbonylation of other oxygen-containing heterocumulenes. As expected, sulfur-atom and nitrene-group transfer were realized from carbonyl sulfide and phenyl isocyanate, respectively (eqs 3 and 4).…”

Section: Reaction With Heterocumulene Electrophilesmentioning

confidence: 99%

Late Metal Carbene Complexes Generated by Multiple C−H Activations: Examining the Continuum of M═C Bond Reactivity

2009

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Unactivated C(sp(3))-H bonds are ubiquitous in organic chemicals and hydrocarbon feedstocks. However, these resources remain largely untapped, and the development of efficient homogeneous methods for hydrocarbon functionalization by C-H activation is an attractive and unresolved challenge for synthetic chemists. Transition-metal catalysis offers an attractive possible means for achieving selective, catalytic C-H functionalization given the thermodynamically favorable nature of many desirable partial oxidation schemes and the propensity of transition-metal complexes to cleave C-H bonds. Selective C-H activation, typically by a single cleavage event to produce M-C(sp(3)) products, is possible through myriad reported transition-metal species. In contrast, several recent reports have shown that late transition metals may react with certain substrates to perform multiple C-H activations, generating M=C(sp(2)) complexes for further elaboration. In light of the rich reactivity of metal-bound carbenes, such a route could open a new manifold of reactivity for catalytic C-H functionalization, and we have targeted this strategy in our studies. In this Account, we highlight several early examples of late transition-metal complexes that have been shown to generate metal-bound carbenes by multiple C-H activations and briefly examine factors leading to the selective generation of metal carbenes through this route. Using these reports as a backdrop, we focus on the double C-H activation of ethers and amines at iridium complexes supported by Ozerov's amidophosphine PNP ligand (PNP = [N(2-P(i)Pr(2)-4-Me-C(6)H(3))(2)](-)), allowing isolation of unusual square-planar iridium(I) carbenes. These species exhibit reactivity that is distinct from the archetypal Fischer and Schrock designations. We present experimental and theoretical studies showing that, like the classical square-planar iridium(I) organometallics, these complexes are best described as nucleophilic at iridium. We discuss the classification of this reactivity in the context of a scheme originally delineated by Roper. These "Roper-type" carbenes perform a number of multiple-bond metatheses leading to atom and group transfer from electrophilic heterocumulene (e.g., CO(2), CS(2), PhNCS) and diazo (e.g., N(2)O, AdN(3)) reagents. In one instance, we have extended this methodology to a process for catalytic C-H functionalization by a double C-H activation-group transfer process. Although the scope of these reactions is currently limited, these new pathways may find broader utility as the reactivity of late-metal carbenes continues to be explored. Examination of alternative transition metals and supporting ligand sets will certainly be important. Nonetheless, our findings show that carbene generation by double C-H activation is a viable strategy for C-H functionalization, leading to products not accessible through traditional C(sp(3))-H activation pathways.

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Reversible, nicht metallunterstützte Bindung von Kohlendioxid durch frustrierte Lewis‐Paare

et al. 2009

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Oxygen Atom “Cut and Paste” from Carbon Dioxide to a Fischer Carbene Complex

Cited by 16 publications

References 43 publications

Strongly Polarized Iridium^δ−–Aluminum^δ+ Pairs: Unconventional Reactivity Patterns Including CO₂ Cooperative Reductive Cleavage

Strongly Polarized Iridium^δ−–Aluminum^δ+ Pairs: Unconventional Reactivity Patterns Including CO₂ Cooperative Reductive Cleavage

Late Metal Carbene Complexes Generated by Multiple C−H Activations: Examining the Continuum of M═C Bond Reactivity

Reversible, nicht metallunterstützte Bindung von Kohlendioxid durch frustrierte Lewis‐Paare

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Oxygen Atom “Cut and Paste” from Carbon Dioxide to a Fischer Carbene Complex

Cited by 16 publications

References 43 publications

Strongly Polarized Iridiumδ−–Aluminumδ+ Pairs: Unconventional Reactivity Patterns Including CO2 Cooperative Reductive Cleavage

Strongly Polarized Iridiumδ−–Aluminumδ+ Pairs: Unconventional Reactivity Patterns Including CO2 Cooperative Reductive Cleavage

Late Metal Carbene Complexes Generated by Multiple C−H Activations: Examining the Continuum of M═C Bond Reactivity

Reversible, nicht metallunterstützte Bindung von Kohlendioxid durch frustrierte Lewis‐Paare

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Strongly Polarized Iridium^δ−–Aluminum^δ+ Pairs: Unconventional Reactivity Patterns Including CO₂ Cooperative Reductive Cleavage

Strongly Polarized Iridium^δ−–Aluminum^δ+ Pairs: Unconventional Reactivity Patterns Including CO₂ Cooperative Reductive Cleavage