A CW‐EPR, ENDOR and special TRIPLE resonance study of a novel magnesium ketyl radical

Murphy, D. M.; McDyre, Lucia; Carter, Emma; Stasch, Andreas; Jones, Cameron

doi:10.1002/mrc.2721

Cited by 16 publications

(11 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A close analogue to 22 is the complex studied by Murphy et al, L dipp Mg(DMAP)(OCPh 2 ), where DMAP = 4-dimethylaminopyridine . This compound can be formally described as Mg(I) with coordinated benzophenone or, more realistically, as Mg(II) with a coordinated benzophenone radical anion.…”

Section: Resultsmentioning

confidence: 99%

Cooperative Activation of CO₂ and Epoxide by a Heterobinuclear Al–Fe Complex via Radical Pair Mechanisms

et al. 2022

View full text Add to dashboard Cite

Activation of inert molecules like CO2 is often mediated by cooperative chemistry between two reactive sites within a catalytic assembly, the most common form of which is Lewis acid/base bifunctionality observed in both natural metalloenzymes and synthetic systems. Here, we disclose a heterobinuclear complex with an Al–Fe bond that instead activates CO2 and other substrates through cooperative behavior of two radical intermediates. The complex Ldipp(Me)AlFp (2, Ldipp = HC{(CMe)(2,6- i Pr2C6H3N)}2, Fp = FeCp(CO)2, Cp = η5-C5H5) was found to insert CO2 and cyclohexene oxide, producing LdippAl(Me)(μ:κ2-O2C)Fp (3) and LdippAl(Me)(μ-OC6H10)Fp (4), respectively. Detailed mechanistic studies indicate unusual pathways in which (i) the Al–Fe bond dissociates homolytically to generate formally AlII and FeI metalloradicals, then (ii) the metalloradicals add to substrate in a pairwise fashion initiated by O-coordination to Al. The accessibility of this unusual mechanism is aided, in part, by the redox noninnocent nature of Ldipp that stabilizes the formally AlII intermediates, instead giving them predominantly AlIII-like physical character. The redox noninnocent nature of the radical intermediates was elucidated through direct observation of LdippAl(Me)(OCPh2) (22), a metalloradical species generated by addition of benzophenone to 2. Complex 22 was characterized by X-band EPR, Q-band EPR, and ENDOR spectroscopies as well as computational modeling. The “radical pair” pathway represents an unprecedented mechanism for CO2 activation.

show abstract

Section: Resultsmentioning

confidence: 99%

Cooperative Activation of CO₂ and Epoxide by a Heterobinuclear Al–Fe Complex via Radical Pair Mechanisms

et al. 2022

View full text Add to dashboard Cite

show abstract

“…)Ph 2 ] 7c. 19 Treating the dimer 11 with two equivalents of tert ‐butyl isocyanate yields the colorless C‐C‐coupled product [(LMg) 2 ( t BuNCO) 2 ] ( 13 ) with a bridging N , N ′‐di‐ tert ‐butyloxamide fragment with N,N′ and O,O′ coordination modes to the Mg 2+ centers (Scheme ). The complex was structurally characterized,12 and the 1 H, 13 C{ 1 H} and 31 P{ 1 H} NMR spectra show two diiminophosphinate ligand environments, and one tert ‐butyl environment in 1 H and 13 C{ 1 H} NMR spectra that support the retention of the overall solid‐state structure in solution.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of a Dimeric Magnesium(I) Compound by an Mg^I/Mg^II Redox Reaction

Stasch

2014

Angew Chem Int Ed

Self Cite

View full text Add to dashboard Cite

The synthesis of dimeric magnesium(I) compounds of the general type RMgMgR (R=monoanionic substituent) is still a challenging synthetic task and limited to few examples with sterically demanding ligands with delocalized CN-frameworks that all have been accessed by Na or K metal reduction of magnesium(II) halide precursors. Here we report on the synthesis of a novel diiminophosphinato magnesium(I) compound that has been synthesized by a facile redox reaction using a known magnesium(I) complex. The synthetic strategy may be applicable to other ligand systems and can help expand the class of low oxidation state magnesium complexes even if reductions with Na or K are unsuccessful. The new dimeric magnesium(I) complex has been structurally characterized and undergoes a C-C coupling reaction with tert-butylisocyanate.

show abstract

“…56,78 The only reduction of an unsaturated substrate that has not yielded a dinuclear complex is that of benzophenone with 4, which afforded the stable purple-blue magnesium ketyl complex, 34, after addition of DMAP to the reaction mixture. 79, 80 All of the above-mentioned reduction reactions were carried out in non-coordinating solvents, and it is likely that those involving the functionalised substrates proceed via coordination of the substrate to one or both of the Mg centres of the dimer prior to its reduction or reductive coupling. This proposal is based on the observation that the double reduction of CyN C NCy with 1 to give 5 is rapid, even below -50 • C, 54 whereas it does not proceed at ambient temperature in THF.…”

Section: Reductions Of Unsaturated Organic Substratesmentioning

confidence: 99%

Stable dimeric magnesium(i) compounds: from chemical landmarks to versatile reagents

2011

Self Cite

View full text Add to dashboard Cite

The chemistry of the s-block metals is dominated by the +1 oxidation state for the Alkali metals (group 1) and the +2 oxidation state for the Alkaline Earth metals (group 2). In recent years, a series of stable dimeric magnesium(I) compounds has been prepared and their chemistry has started to develop. These complexes feature "deformable" Mg-Mg single bonds and are stabilised by sterically demanding and chelating anionic N-ligands that prevent their disproportionation. They have rapidly proven useful in organic and organometallic/inorganic reduction reactions as hydrocarbon soluble, stoichiometric, selective and safe reducing agents. The scope of this perspective focuses on stable molecular compounds of the general type LMgMgL and describes their synthesis, structures, theoretical and spectroscopic studies as well as their further chemistry. Also, comparisons are drawn with related complexes including magnesium(II) hydrides and dimeric zinc(I) compounds.

show abstract

A CW‐EPR, ENDOR and special TRIPLE resonance study of a novel magnesium ketyl radical

Cited by 16 publications

References 19 publications

Cooperative Activation of CO₂ and Epoxide by a Heterobinuclear Al–Fe Complex via Radical Pair Mechanisms

Cooperative Activation of CO₂ and Epoxide by a Heterobinuclear Al–Fe Complex via Radical Pair Mechanisms

Synthesis of a Dimeric Magnesium(I) Compound by an Mg^I/Mg^II Redox Reaction

Stable dimeric magnesium(i) compounds: from chemical landmarks to versatile reagents

Contact Info

Product

Resources

About

A CW‐EPR, ENDOR and special TRIPLE resonance study of a novel magnesium ketyl radical

Cited by 16 publications

References 19 publications

Cooperative Activation of CO2 and Epoxide by a Heterobinuclear Al–Fe Complex via Radical Pair Mechanisms

Cooperative Activation of CO2 and Epoxide by a Heterobinuclear Al–Fe Complex via Radical Pair Mechanisms

Synthesis of a Dimeric Magnesium(I) Compound by an MgI/MgII Redox Reaction

Stable dimeric magnesium(i) compounds: from chemical landmarks to versatile reagents

Contact Info

Product

Resources

About

Cooperative Activation of CO₂ and Epoxide by a Heterobinuclear Al–Fe Complex via Radical Pair Mechanisms

Cooperative Activation of CO₂ and Epoxide by a Heterobinuclear Al–Fe Complex via Radical Pair Mechanisms

Synthesis of a Dimeric Magnesium(I) Compound by an Mg^I/Mg^II Redox Reaction