Heterobimetallic Pd–K carbene complexes via one-electron reductions of palladium radical carbenes

Cui, Peng; Hoffbauer, Melissa R.; Vyushkova, Mariya; Iluc, Vlad M.

doi:10.1039/c6sc00948d

Cited by 28 publications

(31 citation statements)

References 83 publications

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“…1 PMe3 cleanly reacts with 1 atm. of CO 2 gas to yield a single product 5 PMe3 as determined by 31 P NMR spectroscopy (Scheme 2), which exhibited two inequivalent phosphorus centers in a 2:1 ratio at 44.3 and -14.8 ppm, respectively, with clear 2 J P-P coupling (36 Hz), consistent with the structure depicted. The 1 H NMR spectrum is sharp and well resolved, unlike that of 5 NCtBu, suggesting release of CO 2 is slower on this timescale in 5 PMe3.…”

supporting

confidence: 54%

“…The resulting suspension was decanted, and the black crystals of the title compound were washed with 2x2mL of cold (-30 o C) THF and 2x10mL of n-pentane. Material prepared in this way is pure by31 P{ 1 H} NMR. Trace THF contamination can be removed by additional pentane washed Further purification is not possible due to the vacuum sensitivity of the compound.…”

mentioning

confidence: 99%

“…31 P NMR (203 MHz, Benzene-d 6 ) δ 71.1.1 H NMR (500 MHz, Benzene-d 6 ) δ 7.36 -7.30 (m, 2H, Ar-H), 7.14 -7.10 (m, 4H Ar-H), 2.34 (ddt, J = 14.0, 8.7, 6.9 Hz, 2H, P-CH-(CH 3 ) 2 ), 1.86 (ddt, J = 15.8, 8.5, 4.3 Hz, 2H, P-CH-(CH 3 ) 2 ), 1.67 (s, 6H, ((Ar) 2 C(CH 3 ) 2 ), 1.30 (dd, J = 15.8, 6.9 Hz, 6H, P-CH-(CH 3 ) 2 ), 1.12 (dd, J =…”

mentioning

confidence: 99%

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Divergent Reactivity of CO2 and CO and Related Substrates at the Nickel Carbon Double Bond of (PCcarbeneP)Ni(II) Pincer Complexes

LaPierre¹,

Piers²,

Gendy³

2018

Preprint

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ABSTRACT:The addition of carbon monoxide (CO), carbon dioxide (CO 2 ) and isoelectronic isocyanide and isocyanates to the nickel carbene bond in PC carbene P pincer complexes is reported. For CO and CNR, irreversible group transfer reactions are observed, while for CO 2 , a reversible 2+2 addition to the carbene moiety occurs. The course of the CO and CO 2 reactions are strongly affected by the nature of the PC carbene P pincer ligand framework and a new more rigid ligand based on a 10,10-dimethyl-9,10-dihydroanthracene core was designed in order to study these reactions, illustrating the profound effect of small changes in ligand structure on reaction outcomes.The fundamental reactivity of carbon dioxide at transition metal centers is intensely pursued with the aim of the development of methods utilizing CO 2 as a practical C 1 source. 1 In nature, the interconversion of CO 2 and CO, the primary industrial C 1 source, is efficiently accomplished enzymatically through the action of [NiFe]-carbon monoxide dehydrogenase (CODH). 1 The proposed mechanism of action of (CODH) is believed to proceed via CO 2 binding to a square planar nickel center at the [NiFe 4 S 4 ] active site. 2 As such the coordination chemistry of CO 2 and CO at nickel centers supported by pincer ligands to rigorously enforce a square planar geometry is of particular interest, and has been widely explored. [3][4][5][6][7][8][9][10][11][12][13] Notably, the isolation of key proposed intermediates in selective reduction of CO 2 to CO, 3 and a closed synthetic cycle for the reduction CO 2 to CO have recently been realized using PNP pincer ligand supported nickel complexes. 4,9 Despite the rich coordination chemistry of CO 2 , 14 there is a relative dearth of examples of CO 2 bonding and activation using metal-ligand cooperation. 15 Many of these examples consist of 1,3-activation of CO 2 at dearomatized PNP or PNN pincer complexes of second and third row transition metals, 16-18 though examples have been noted with Fe 19 and Ni, 20 and the formal 1,2-addition has been observed at pincer ligand supported Mo and W amides. 21 In a second mode of activation, the double insertion of CO 2 into a three coordinate Ni carbene and imido complexes complex is proposed to proceed first through the 2+2 addition of CO 2 to the Ni=X double bond, with direct evidence for 2+2 reactivity in the case of Ni-imido complexes. [22][23] We have reported the (PC carbene P)Ni complex 1 L1 , containing an unusual carbene central donor 24 (Scheme 1) which readily participates in metal-ligand cooperation in the activation of H-X (X=NH 2 , H, OH, OMe, CCPh, HSiR 3 ) type bonds. [25][26] In all cases the bond is cleaved across the Ni=C bond in a 1,2 fashion, with regioselectivity favoring addition of the electrophilic end of the polarized H-X bond to the carbene carbon. Closely related Pd complexes are also active in H-X bond activation chemistry, [27][28][29][30] and their redox properties and activity in frustrated-Lewis-pair type chemistry have been explored. 31-34 However, th...

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confidence: 54%

mentioning

confidence: 99%

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Divergent Reactivity of CO2 and CO and Related Substrates at the Nickel Carbon Double Bond of (PCcarbeneP)Ni(II) Pincer Complexes

LaPierre¹,

Piers²,

Gendy³

2018

Preprint

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“…[35][36][37][38][39] As shown in Scheme 1, these reactions were more tractable and clean; reaction of 1 L1 with excess tert-butyl isocyanate in C 6 D 6 resulted in an immediate color change from dark orange to blackpurple. 31 P{ 1 H} NMR spectroscopy revealed a single product 2 characterized by a singlet at 29.5 ppm. The 1 H NMR spectrum showed peaks consistent in a decrease in symmetry from C 2v to C s , two distinct tert-butyl environments integrating 1:1, and no evidence of free tert-butyl nitrile.…”

Section: Treatment Of the Tert-butyl Nitrile Ligated (Pc Carbene P)nimentioning

confidence: 99%

“…Closely related Pd complexes are also active in H-X bond activation chemistry, [27][28][29][30] and their redox properties and activity in frustrated-Lewis-pair type chemistry have been explored. [31][32][33][34] However, there has been no investigation of the reactivity of CO 2 or CO with the PCP complexes of the group 10 metals. Here we present the reactivity of 1 L1 with with CO 2, CO and isoelectronic isocyanate and isocyanide analogues and introduce a key ligand modification that dictates the course of CO 2 and CO activation by these platforms.…”

mentioning

confidence: 99%

Divergent Reactivity of CO2 and CO and Related Substrates at the Nickel Carbon Double Bond of (PCcarbeneP)Ni(II) Pincer Complexes

LaPierre¹,

Piers²,

Gendy³

2018

Preprint

View full text Add to dashboard Cite

The addition of carbon monoxide (CO), carbon dioxide (CO2) and isoelectronic isocyanide and isocyanates to the nickel carbene bond in PCcarbeneP pincer complexes is reported. For CO and CNR, irreversible group transfer reactions are observed, while for CO2, a reversible 2+2 addition to the carbene moiety occurs. The course of the CO and CO2 reactions are strongly affected by the nature of the PCcarbeneP pincer ligand framework and a new more rigid ligand based on a 10,10-dimethyl-9,10-dihydroanthracene core was designed in order to study these reactions, illustrating the profound effect of small changes in ligand structure on reaction outcomes.

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Access to and Reactivity of Fe⁰, Fe^−I, Fe^I, and Fe^II PC_carbeneP Pincer Complexes

et al. 2021

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Despite their promising metal–ligand cooperative reactivity, PCcarbeneP pincer ligands are rarely reported for first‐row transition‐metal centres. Using a dehydration methodology, we report access to an Fe0 PCcarbeneP pincer complex (1) that proceeds via an isolated α‐hydroxylalkyl hydrido complex (3). Reversible carbonyl migration to the carbene position in 1 is found to allow coordination chemistry and E−H bond addition (E=H, B, Cl) across the iron–carbene linkage, representing a unique mechanism for metal–ligand cooperativity. The PCcarbeneP pincer ligand is also found to stabilize formal FeII, FeI, and Fe−I oxidation states, as demonstrated with synthesis and characterization of the complexes [11‐X][BArF20] (X=Br, I), 12, and K[13]. Compound K[13] is found to be highly reactive, and abstracts hydrogen from a range of aliphatic C−H sources. Computational analysis by DFT suggests that the formal FeI and Fe−I complexes contain significant carbene radical character. The ability of the PCcarbeneP ligand scaffold to partake in metal–ligand cooperativity and to support a range of iron oxidation states renders it as potentially useful in many catalytic applications.

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Heterobimetallic Pd–K carbene complexes via one-electron reductions of palladium radical carbenes

Abstract: Unprecedented sequential substitution/reduction synthetic strategy on the Pd radical carbenes afforded heterobimetallic Pd–K carbene complexes, which features novel Pd–Ccarbene–K structural moieties.

Cited by 28 publications

References 83 publications

Divergent Reactivity of CO2 and CO and Related Substrates at the Nickel Carbon Double Bond of (PCcarbeneP)Ni(II) Pincer Complexes

Divergent Reactivity of CO2 and CO and Related Substrates at the Nickel Carbon Double Bond of (PCcarbeneP)Ni(II) Pincer Complexes

Divergent Reactivity of CO2 and CO and Related Substrates at the Nickel Carbon Double Bond of (PCcarbeneP)Ni(II) Pincer Complexes

Access to and Reactivity of Fe⁰, Fe^−I, Fe^I, and Fe^II PC_carbeneP Pincer Complexes

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Heterobimetallic Pd–K carbene complexes via one-electron reductions of palladium radical carbenes

Abstract: Unprecedented sequential substitution/reduction synthetic strategy on the Pd radical carbenes afforded heterobimetallic Pd–K carbene complexes, which features novel Pd–Ccarbene–K structural moieties.

Cited by 28 publications

References 83 publications

Divergent Reactivity of CO2 and CO and Related Substrates at the Nickel Carbon Double Bond of (PCcarbeneP)Ni(II) Pincer Complexes

Divergent Reactivity of CO2 and CO and Related Substrates at the Nickel Carbon Double Bond of (PCcarbeneP)Ni(II) Pincer Complexes

Divergent Reactivity of CO2 and CO and Related Substrates at the Nickel Carbon Double Bond of (PCcarbeneP)Ni(II) Pincer Complexes

Access to and Reactivity of Fe0, Fe−I, FeI, and FeII PCcarbeneP Pincer Complexes

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Access to and Reactivity of Fe⁰, Fe^−I, Fe^I, and Fe^II PC_carbeneP Pincer Complexes