Michael L. Neidig

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Unusual S=1 Four‐Coordinate Fe(IV) Complexes Supported by Bisamide Ligands: Syntheses, Characterization, and Electronic Structures

Bufan Zhang, Justin P. Joyce, Nikki J. Wolford, William W. Brennessel, more

Angewandte Chemie International Edition > 63 > 36 > n/a - n/a

The catalytic relevance of Fe(IV) species in non‐heme iron catalysis has motivated synthetic advances in well‐defined five‐ and six‐coordinate Fe(IV) complexes for a better understanding of their fundamental electronic structures and reactivities. Herein, we report the syntheses of FeDipp₂ and FeMes₂, a pair of unusual four‐coordinate non‐heme formally Fe(IV) complexes with S=1 ground states supported...

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Unusual S=1 Four‐Coordinate Fe(IV) Complexes Supported by Bisamide Ligands: Syntheses, Characterization, and Electronic Structures

Bufan Zhang, Justin P. Joyce, Nikki J. Wolford, William W. Brennessel, more

Angewandte Chemie > 136 > 36 > n/a - n/a

The catalytic relevance of Fe(IV) species in non‐heme iron catalysis has motivated synthetic advances in well‐defined five‐ and six‐coordinate Fe(IV) complexes for a better understanding of their fundamental electronic structures and reactivities. Herein, we report the syntheses of FeDipp₂ and FeMes₂, a pair of unusual four‐coordinate non‐heme formally Fe(IV) complexes with S=1 ground states supported...

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A TMEDA–Iron Adduct Reaction Manifold in Iron‐Catalyzed C(sp²)−C(sp³) Cross‐Coupling Reactions

Nikki J. Bakas, Jeffrey D. Sears, William W. Brennessel, Michael L. Neidig

Angewandte Chemie International Edition > 61 > 15 > n/a - n/a

Herein, we expand the current molecular‐level understanding of one of the most important and effective additives in iron‐catalyzed cross‐coupling reactions, N,N,N′,N′‐tetramethylethylenediamine (TMEDA). Focusing on relevant phenyl and ethyl Grignard reagents and slow nucleophile addition protocols commonly used in effective catalytic systems, TMEDA‐iron(II)‐aryl intermediates are identified via in...

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A TMEDA–Iron Adduct Reaction Manifold in Iron‐Catalyzed C(sp²)−C(sp³) Cross‐Coupling Reactions

Nikki J. Bakas, Jeffrey D. Sears, William W. Brennessel, Michael L. Neidig

Angewandte Chemie > 134 > 15 > n/a - n/a

Herein, we expand the current molecular‐level understanding of one of the most important and effective additives in iron‐catalyzed cross‐coupling reactions, N,N,N′,N′‐tetramethylethylenediamine (TMEDA). Focusing on relevant phenyl and ethyl Grignard reagents and slow nucleophile addition protocols commonly used in effective catalytic systems, TMEDA‐iron(II)‐aryl intermediates are identified via in...

article

NHC Effects on Reduction Dynamics in Iron‐Catalyzed Organic Transformations**

Nikki J. Wolford, Salvador B. Muñoz, Peter G. N. Neate, William W. Brennessel, more

Chemistry – A European Journal > 27 > 54 > 13651 - 13658

The high abundance, low toxicity and rich redox chemistry of iron has resulted in a surge of iron‐catalyzed organic transformations over the last two decades. Within this area, N‐heterocyclic carbene (NHC) ligands have been widely utilized to achieve high yields across reactions including cross‐coupling and C−H alkylation, amongst others. Central to the development of iron‐NHC catalytic methods is...

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TMEDA in Iron‐Catalyzed Hydromagnesiation: Formation of Iron(II)‐Alkyl Species for Controlled Reduction to Alkene‐Stabilized Iron(0)

Peter G. N. Neate, Mark D. Greenhalgh, William W. Brennessel, Stephen P. Thomas, more

Angewandte Chemie > 132 > 39 > 17218 - 17224

N,N,N′,N′‐Tetramethylethylenediamine (TMEDA) has been one of the most prevalent and successful additives used in iron catalysis, finding application in reactions as diverse as cross‐coupling, C−H activation, and borylation. However, the role that TMEDA plays in these reactions remains largely undefined. Herein, studying the iron‐catalyzed hydromagnesiation of styrene derivatives using TMEDA has provided...

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TMEDA in Iron‐Catalyzed Hydromagnesiation: Formation of Iron(II)‐Alkyl Species for Controlled Reduction to Alkene‐Stabilized Iron(0)

Peter G. N. Neate, Mark D. Greenhalgh, William W. Brennessel, Stephen P. Thomas, more

Angewandte Chemie International Edition > 59 > 39 > 17070 - 17076

N,N,N′,N′‐Tetramethylethylenediamine (TMEDA) has been one of the most prevalent and successful additives used in iron catalysis, finding application in reactions as diverse as cross‐coupling, C−H activation, and borylation. However, the role that TMEDA plays in these reactions remains largely undefined. Herein, studying the iron‐catalyzed hydromagnesiation of styrene derivatives using TMEDA has provided...

article

The Exceptional Diversity of Homoleptic Uranium–Methyl Complexes

Jeffrey D. Sears, Dumitru‐Claudiu Sergentu, Tessa M. Baker, William W. Brennessel, more

Angewandte Chemie International Edition > 59 > 32 > 13586 - 13590

Homoleptic σ‐bonded uranium–alkyl complexes have been a synthetic target since the Manhattan Project. The current study describes the synthesis and characterization of several unprecedented uranium–methyl complexes. Amongst these complexes, the first example of a homoleptic uranium–alkyl dimer, [Li(THF)₄]₂[U₂(CH₃)₁₀], as well as a seven‐coordinate uranium–methyl monomer, {Li(OEt₂)Li(OEt₂)₂UMe₇Li}_n...

article

The Exceptional Diversity of Homoleptic Uranium–Methyl Complexes

Jeffrey D. Sears, Dumitru‐Claudiu Sergentu, Tessa M. Baker, William W. Brennessel, more

Angewandte Chemie > 132 > 32 > 13688 - 13692

Homoleptic σ‐bonded uranium–alkyl complexes have been a synthetic target since the Manhattan Project. The current study describes the synthesis and characterization of several unprecedented uranium–methyl complexes. Amongst these complexes, the first example of a homoleptic uranium–alkyl dimer, [Li(THF)₄]₂[U₂(CH₃)₁₀], as well as a seven‐coordinate uranium–methyl monomer, {Li(OEt₂)Li(OEt₂)₂UMe₇Li}_n...

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Homoleptic Aryl Complexes of Uranium (IV)

Nikki J. Wolford, Dumitru‐Claudiu Sergentu, William W. Brennessel, Jochen Autschbach, more

Angewandte Chemie > 131 > 30 > 10372 - 10376

The synthesis and characterization of sterically unencumbered homoleptic organouranium aryl complexes containing U−C σ‐bonds has been of interest to the chemical community for over 70 years. Reported herein are the first structurally characterized, sterically unencumbered homoleptic uranium (IV) aryl‐ate species of the form [U(Ar)₆]²⁻ (Ar=Ph, p‐tolyl, p‐Cl‐Ph). Magnetic circular dichroism (MCD) spectroscopy...

article

Homoleptic Aryl Complexes of Uranium (IV)

Nikki J. Wolford, Dumitru‐Claudiu Sergentu, William W. Brennessel, Jochen Autschbach, more

Angewandte Chemie International Edition > 58 > 30 > 10266 - 10270

The synthesis and characterization of sterically unencumbered homoleptic organouranium aryl complexes containing U−C σ‐bonds has been of interest to the chemical community for over 70 years. Reported herein are the first structurally characterized, sterically unencumbered homoleptic uranium (IV) aryl‐ate species of the form [U(Ar)₆]²⁻ (Ar=Ph, p‐tolyl, p‐Cl‐Ph). Magnetic circular dichroism (MCD) spectroscopy...

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The Effect of β‐Hydrogen Atoms on Iron Speciation in Cross‐Couplings with Simple Iron Salts and Alkyl Grignard Reagents

Jeffrey D. Sears, Salvador B. Muñoz, Stephanie L. Daifuku, Ari A. Shaps, more

Angewandte Chemie > 131 > 9 > 2795 - 2799

The effects of β‐hydrogen‐containing alkyl Grignard reagents in simple ferric salt cross‐couplings have been elucidated. The reaction of FeCl₃ with EtMgBr in THF leads to the formation of the cluster species [Fe₈Et₁₂]²⁻, a rare example of a structurally characterized metal complex with bridging ethyl ligands. Analogous reactions in the presence of NMP, a key additive for effective cross‐coupling with...

article

The Effect of β‐Hydrogen Atoms on Iron Speciation in Cross‐Couplings with Simple Iron Salts and Alkyl Grignard Reagents

Jeffrey D. Sears, Salvador B. Muñoz, Stephanie L. Daifuku, Ari A. Shaps, more

Angewandte Chemie International Edition > 58 > 9 > 2769 - 2773

The effects of β‐hydrogen‐containing alkyl Grignard reagents in simple ferric salt cross‐couplings have been elucidated. The reaction of FeCl₃ with EtMgBr in THF leads to the formation of the cluster species [Fe₈Et₁₂]²⁻, a rare example of a structurally characterized metal complex with bridging ethyl ligands. Analogous reactions in the presence of NMP, a key additive for effective cross‐coupling with...

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The N‐Methylpyrrolidone (NMP) Effect in Iron‐Catalyzed Cross‐Coupling with Simple Ferric Salts and MeMgBr

Salvador B. Muñoz, Stephanie L. Daifuku, Jeffrey D. Sears, Tessa M. Baker, more

Angewandte Chemie > 130 > 22 > 6606 - 6610

The use of N‐methylpyrrolidone (NMP) as a co‐solvent in ferric salt catalyzed cross‐coupling reactions is crucial for achieving the highly selective, preparative scale formation of cross‐coupled product in reactions utilizing alkyl Grignard reagents. Despite the critical importance of NMP, the molecular level effect of NMP on in situ formed and reactive iron species that enables effective catalysis...

article

The N‐Methylpyrrolidone (NMP) Effect in Iron‐Catalyzed Cross‐Coupling with Simple Ferric Salts and MeMgBr

Salvador B. Muñoz, Stephanie L. Daifuku, Jeffrey D. Sears, Tessa M. Baker, more

Angewandte Chemie International Edition > 57 > 22 > 6496 - 6500

The use of N‐methylpyrrolidone (NMP) as a co‐solvent in ferric salt catalyzed cross‐coupling reactions is crucial for achieving the highly selective, preparative scale formation of cross‐coupled product in reactions utilizing alkyl Grignard reagents. Despite the critical importance of NMP, the molecular level effect of NMP on in situ formed and reactive iron species that enables effective catalysis...

article

Resident holes and electrons at organic/conductor and organic/organic interfaces: An electron paramagnetic resonance investigation

Chen Zhang, Stephanie L. Daifuku, Michael L. Neidig, Alfred P. Marchetti

Organic Electronics > 2016 > 37 > C > 379-385

A number of organic/conductor and organic/organic interfaces have been examined by EPR spectroscopy to ascertain the areal concentration of organic ions at the interface. Organic hole transport materials such as NPB and TAPC at an interface with MoO_x are found to have areal concentrations on the order of 10¹⁴ cations per cm². C₆₀ at an interface with MoO_x creates ≈10¹³ cations per cm² depending on...

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Direct observation of ICT cations at the HTL/transparent semiconductor interface

Stephanie L. Daifuku, Chris Favaro, Alfred P. Marchetti, Michael L. Neidig

Organic Electronics > 2014 > 15 > 12 > 3761-3765

The cation density at the interface of a transparent anode and an organic layer has been measured for several hole transport (HT) materials. The number of cations at the interface of ITO:MoO_x with rubrene, NPB, m-MTDATA and TCTA was found to range from 8×10¹³ to 1.5×10¹⁴percm² in freshly prepared devices. These values decreased by about 25% after one month. These cations are part of the dipole layer...

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Iron Dicarbonyl Complexes Featuring Bipyridine‐Based PNN Pincer Ligands with Short Interpyridine CC Bond Lengths: Innocent or Non‐Innocent Ligand?

Thomas Zell, Petr Milko, Kathlyn L. Fillman, Yael Diskin‐Posner, more

Chemistry – A European Journal > 20 > 15 > 4403 - 4413

A series of iron dicarbonyl complexes with bipyridine‐based PNN pincer ligands were synthesized and characterized by multinuclear NMR spectroscopy (¹H, ¹³C, ¹⁵N, ³¹P), IR spectroscopy, cyclic voltammetry, ⁵⁷Fe Mössbauer spectroscopy, XPS spectroscopy, and single‐crystal X‐ray diffraction. The complexes with the general formula [(R‐PNN)Fe(CO)₂] (5: R‐PNN=tBu‐PNN=6‐[(di‐tert‐butylphosphino)methyl]‐2,2′‐bipyridine,...

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Efficient Nazarov Cyclization/Wagner–Meerwein Rearrangement Terminated by a Cu^II‐Promoted Oxidation: Synthesis of 4‐Alkylidene Cyclopentenones

David Lebœuf, Eric Theiste, Vincent Gandon, Stephanie L. Daifuku, more

Chemistry – A European Journal > 19 > 15 > 4842 - 4848

The discovery and elucidation of a new Nazarov cyclization/Wagner–Meerwein rearrangement/oxidation sequence is described that constitutes an efficient strategy for the synthesis of 4‐alkylidene cyclopentenones. DFT computations and EPR experiments were conducted to gain further mechanistic insight into the reaction pathways.

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Covalency in f-element complexes

Michael L. Neidig, David L. Clark, Richard L. Martin

Coordination Chemistry Reviews > 2013 > 257 > 2 > 394-406

The presence of covalency in complexes of the 4f and 5f elements has been a source of intense research and controversy. In addition to academic interest in this debate, there is an industrial motivation for better understanding of bonding in f-element complexes due to the need to separate trivalent trans-plutonium elements from trivalent lanthanide fission products in advanced nuclear fuel cycles...

INFONA - science communication portal

Search results for: Michael L. Neidig

Unusual S=1 Four‐Coordinate Fe(IV) Complexes Supported by Bisamide Ligands: Syntheses, Characterization, and Electronic Structures

Unusual S=1 Four‐Coordinate Fe(IV) Complexes Supported by Bisamide Ligands: Syntheses, Characterization, and Electronic Structures

A TMEDA–Iron Adduct Reaction Manifold in Iron‐Catalyzed C(sp²)−C(sp³) Cross‐Coupling Reactions

A TMEDA–Iron Adduct Reaction Manifold in Iron‐Catalyzed C(sp²)−C(sp³) Cross‐Coupling Reactions

NHC Effects on Reduction Dynamics in Iron‐Catalyzed Organic Transformations**

TMEDA in Iron‐Catalyzed Hydromagnesiation: Formation of Iron(II)‐Alkyl Species for Controlled Reduction to Alkene‐Stabilized Iron(0)

TMEDA in Iron‐Catalyzed Hydromagnesiation: Formation of Iron(II)‐Alkyl Species for Controlled Reduction to Alkene‐Stabilized Iron(0)

The Exceptional Diversity of Homoleptic Uranium–Methyl Complexes

The Exceptional Diversity of Homoleptic Uranium–Methyl Complexes

Homoleptic Aryl Complexes of Uranium (IV)

Homoleptic Aryl Complexes of Uranium (IV)

The Effect of β‐Hydrogen Atoms on Iron Speciation in Cross‐Couplings with Simple Iron Salts and Alkyl Grignard Reagents

The Effect of β‐Hydrogen Atoms on Iron Speciation in Cross‐Couplings with Simple Iron Salts and Alkyl Grignard Reagents

The N‐Methylpyrrolidone (NMP) Effect in Iron‐Catalyzed Cross‐Coupling with Simple Ferric Salts and MeMgBr

The N‐Methylpyrrolidone (NMP) Effect in Iron‐Catalyzed Cross‐Coupling with Simple Ferric Salts and MeMgBr

Resident holes and electrons at organic/conductor and organic/organic interfaces: An electron paramagnetic resonance investigation

Direct observation of ICT cations at the HTL/transparent semiconductor interface

Iron Dicarbonyl Complexes Featuring Bipyridine‐Based PNN Pincer Ligands with Short Interpyridine CC Bond Lengths: Innocent or Non‐Innocent Ligand?

Efficient Nazarov Cyclization/Wagner–Meerwein Rearrangement Terminated by a Cu^II‐Promoted Oxidation: Synthesis of 4‐Alkylidene Cyclopentenones

Covalency in f-element complexes

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