211 results on '"Udo Radius"'
Search Results
2. Nickel boryl complexes and nickel-catalyzed alkyne borylation
- Author
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Lukas Tendera, Felipe Fantuzzi, Todd B. Marder, and Udo Radius
- Subjects
General Chemistry - Abstract
Nickel bis-boryl complexes cis-[Ni(NHC)2(Bcat)2], cis-[Ni(NHC)2(Bpin)2] and cis-[Ni(NHC)2(Beg)2] are presented and the nickel-catalyzed alkyne borylation is reported.
- Published
- 2023
3. Frontispiz: Borane als Wegbereiter zu anionischen cyclischen (Alkyl)(amino)carbenen (Ani‐cAACs)
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Ludwig Zapf, Sven Peters, Udo Radius, and Maik Finze
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General Medicine - Published
- 2023
4. Frontispiece: Boranes Paving the Way to Anionic Cyclic (Alkyl)(amino)carbenes (Ani‐cAACs)
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Ludwig Zapf, Sven Peters, Udo Radius, and Maik Finze
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General Chemistry ,Catalysis - Published
- 2023
5. Boranes Paving the Way to Anionic Cyclic (Alkyl)(amino)carbenes (Ani‐cAACs)
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Ludwig Zapf, Sven Peters, Udo Radius, and Maik Finze
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General Chemistry ,Catalysis - Published
- 2023
6. Borane als Wegbereiter zu anionischen cyclischen (Alkyl)(amino)carbenen (Ani‐cAACs)
- Author
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Ludwig Zapf, Sven Peters, Udo Radius, and Maik Finze
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General Medicine - Published
- 2023
7. Anionic N-heterocyclic carbenes featuring weakly coordinating perfluoroalkylphosphorane moieties
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Ludwig Zapf, Udo Radius, and Maik Finze
- Subjects
Inorganic Chemistry - Abstract
Novel anionic N-heterocyclic carbenes featuring weakly coordinating (C2F5)3PF2− groups at imidazoline were synthesized. These WCA-NHCs are promising ligands with enhanced donor and acceptor properties compared to neutral NHCs.
- Published
- 2023
8. Subvalent group 13 molecules by carbene-induced hydrogen abstraction
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Luis Werner, Andreas Hock, Christian Luz, Melanie Riethmann, and Udo Radius
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Inorganic Chemistry - Abstract
A case study on the selective dehydrogenation of Cp* (Cp* = C5Me5) aluminum and gallium hydrides using N-heterocyclic carbenes and the cyclic(alkyl)(amino)carbene cAACMe is presented.
- Published
- 2023
9. Solution and solid-state studies of hydrogen and halogen bonding with N-heterocyclic carbene supported nickel(<scp>ii</scp>) fluoride complexes
- Author
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Vargini G. Thangavadivale, Lukas Tendera, Rüdiger Bertermann, Udo Radius, Torsten Beweries, and Robin N. Perutz
- Subjects
Physical and Theoretical Chemistry - Abstract
Halogen and hydrogen bonding using bis(carbene) nickel fluoride complexes as acceptors and suitable halogen and hydrogen bond donors is presented, showing interactions that are much stronger than those of related phosphine supported nickel fluorides.
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- 2023
10. N-heterocyclic carbene and cyclic (alkyl)(amino)carbene adducts of plumbanes and plumbylenes
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Michael S. M. Philipp, Rüdiger Bertermann, and Udo Radius
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Inorganic Chemistry - Abstract
The synthesis and characterization of NHC and cAACMe ligated Pb(ii) and Pb(iv) compounds are presented.
- Published
- 2022
11. N-Heterocyclic carbene and cyclic (alkyl)(amino)carbene complexes of vanadium(<scp>iii</scp>) and vanadium(<scp>v</scp>)
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Günther Horrer, Ivo Krummenacher, Sophie Mann, Holger Braunschweig, and Udo Radius
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Inorganic Chemistry - Abstract
The synthesis, characterization, and molecular structures of NHC and cAACMe stabilized V(iii) and V(v) complexes are presented.
- Published
- 2022
12. NHC induced radical formation via homolytic cleavage of B–B bonds and its role in organic reactions
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Laura Kuehn, Ludwig Zapf, Luis Werner, Martin Stang, Sabrina Würtemberger-Pietsch, Ivo Krummenacher, Holger Braunschweig, Emmanuel Lacôte, Todd B. Marder, and Udo Radius
- Subjects
General Chemistry - Abstract
Bis-NHC adducts of the type (NHC)2·B2(OR)4 are sources of boryl radicals of the type NHC–BR2˙, which are formed by homolytic B–B bond cleavage.
- Published
- 2022
13. Cu-mediated vs. Cu-free selective borylation of aryl alkyl sulfones
- Author
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Mingming Huang, Man Tang, Jiefeng Hu, Stephen A. Westcott, Udo Radius, and Todd B. Marder
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Materials Chemistry ,Metals and Alloys ,Ceramics and Composites ,General Chemistry ,Catalysis ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Abstract
Borylation of cyclic aryl–alkyl sulfones gives boronate esters by selective cleavage of C(sp2)–SO2 or C(sp3)–SO2 bonds via Cu-mediated or Cu-free processes.
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- 2022
14. Case Study of N ‐ i Pr versus N ‐Mes Substituted NHC Ligands in Nickel Chemistry: The Coordination and Cyclotrimerization of Alkynes at [Ni(NHC) 2 ]
- Author
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Maximilian W. Kuntze-Fechner, Mirjam J. Krahfuss, Moritz Helm, Udo Radius, and Lukas Tendera
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chemistry.chemical_classification ,Chemistry ,Ligand ,Organic Chemistry ,Alkyne ,General Chemistry ,Bite angle ,Triple bond ,Medicinal chemistry ,Catalysis ,chemistry.chemical_compound ,Phenylacetylene ,Diphenylacetylene ,Pi backbonding - Abstract
A case study on the effect of the employment of two different NHC ligands in complexes [Ni(NHC)2 ] (NHC=i Pr2 ImMe 1Me , Mes2 Im 2) and their behavior towards alkynes is reported. The reaction of a mixture of [Ni2 (i Pr2 ImMe )4 (μ-(η2 : η2 )-COD)] B/ [Ni(i Pr2 ImMe )2 (η4 -COD)] B' or [Ni(Mes2 Im)2 ] 2, respectively, with alkynes afforded complexes [Ni(NHC)2 (η2 -alkyne)] (NHC=i Pr2 ImMe : alkyne=MeC≡CMe 3, H7 C3 C≡CC3 H7 4, PhC≡CPh 5, MeOOCC≡CCOOMe 6, Me3 SiC≡CSiMe3 7, PhC≡CMe 8, HC≡CC3 H7 9, HC≡CPh 10, HC≡C(p-Tol) 11, HC≡C(4-t Bu-C6 H4 ) 12, HC≡CCOOMe 13; NHC=Mes2 Im: alkyne=MeC≡CMe 14, MeOOCC≡CCOOMe 15, PhC≡CMe 16, HC≡C(4-t Bu-C6 H4 ) 17, HC≡CCOOMe 18). Unusual rearrangement products 11 a and 12 a were identified for the complexes of the terminal alkynes HC≡C(p-Tol) and HC≡C(4-t Bu-C6 H4 ), 11 and 12, which were formed by addition of a C-H bond of one of the NHC N-i Pr methyl groups to the C≡C triple bond of the coordinated alkyne. Complex 2 catalyzes the cyclotrimerization of 2-butyne, 4-octyne, diphenylacetylene, dimethyl acetylendicarboxylate, 1-pentyne, phenylacetylene and methyl propiolate at ambient conditions, whereas 1Me is not a good catalyst. The reaction of 2 with 2-butyne was monitored in some detail, which led to a mechanistic proposal for the cyclotrimerization at [Ni(NHC)2 ]. DFT calculations reveal that the differences between 1Me and 2 for alkyne cyclotrimerization lie in the energy profile of the initiation steps, which is very shallow for 2, and each step is associated with only a moderate energy change. The higher stability of 3 compared to 14 is attributed to a better electron transfer from the NHC to the metal to the alkyne ligand for the N-alkyl substituted NHC, to enhanced Ni-alkyne backbonding due to a smaller CNHC -Ni-CNHC bite angle, and to less steric repulsion of the smaller NHC i Pr2 ImMe .
- Published
- 2021
15. N-heterocyclic carbene and cyclic (alkyl)(amino)carbene complexes of molybdenum(IV) and tungsten(IV)
- Author
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Christian Luz, Eduard Glok, Günther Horrer, and Udo Radius
- Subjects
Inorganic Chemistry - Abstract
The synthesis and characterization of N-heterocyclic carbene (NHC) and cyclic (alkyl)(amino)carbene (cAAC) complexes of molybdenum(IV) and tungsten(IV) chloride is reported. Reaction of two equivalents of the NHCs IMes (1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene), IDipp (1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) and IiPr
- Published
- 2022
16. N‐Heterocyclic Carbene and Cyclic (Alkyl)(amino)carbene Adducts of Antimony(III)
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Udo Radius, Krzysztof Radacki, Michael Philipp, and Mirjam J. Krahfuss
- Subjects
Inorganic Chemistry ,chemistry.chemical_classification ,chemistry.chemical_compound ,Antimony ,Chemistry ,chemistry.chemical_element ,ddc:546 ,Medicinal chemistry ,Carbene ,Alkyl ,Adduct - Abstract
A systematic study on Lewis-acid/base adducts of N-heterocyclic carbenes (NHCs) and the cyclic (alkyl)(amino)carbene cAAC\(^{Me}\) (1-(2,6-di-iso-propylphenyl)-3,3,5,5-tetramethyl-pyrrolidin-2-ylidene) with antimony(III) chlorides of the general formula SbCl\(_{2}\)R (R=Cl, Ph, Mes) is presented. The reaction of the NHCs Me\(_{2}\)Im\(^{Me}\) (1,3,4,5-tetra-methyl-imidazolin-2-ylidene), iPr\(_{2}\)Im\(^{Me}\) (1,3-di-isopropyl-4,5-dimethyl-imidazolin-2-ylidene), Mes\(_{2}\)Im, Dipp\(_{2}\)Im (R\(_{2}\)Im=1,3-di-organyl-imidazolin-2-ylidene; Mes=2,4,6-trimethylphenyl, Dipp=2,6-di-isopropylphenyl) and cAAC\(^{Me}\) with antimony(III) compounds SbCl\(_{2}\)R (R=Cl (1), Ph (2) and Mes (3)) yields the adducts NHC ⋅ SbCl\(_{2}\)R (R=Cl (4), Ph (5) and Mes (6); NHC=Me\(_{2}\)Im\(^{Me}\) (a), iPr\(_{2}\)Im\(^{Me}\) (b), Dipp\(_{2}\)Im (c) and Mes\(_{2}\)Im (d)) and cAAC\(^{Me}\) ⋅ SbCl\(_{2}\)R (R=Cl (4 e) and Ph (5 e)). Thermal treatment of (Dipp\(_{2}\)Im) ⋅ SbCl\(_{2}\)Ar (Ar=Ph (5 c) and Mes (6 c)) in benzene leads to isomerization to the backbone coordinated \(^{a}\)NHC-adduct \(^{a}\)Dipp\(_{2}\)Im ⋅ SbCl\(_{2}\)Ar (Ar=Mes (7) and Ph (8)) (\(^{"a"}\) denotes “abnormal” coordination mode of the NHC) in high yields. One of the chloride substituents at antimony of 7 can be abstracted by GaCl3 or Ag[BF\(_{4}\)] to obtain the imidazolium salts [\(^{a}\)Dipp\(_{2}\)Im ⋅ SbClMes][BF\(_{4}\)] (9) and [\(^{a}\)Dipp\(_{2}\)Im ⋅ SbClMes][GaCl\(_{4}\)] (10).
- Published
- 2021
17. [Ni(NHC) 2 ] as a Scaffold for Structurally Characterized trans [H−Ni−PR 2 ] and trans [R 2 P−Ni−PR 2 ] Complexes
- Author
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Michael K. Whittlesey, Sara Sabater, William J. M. Blackaby, Heidi Née Schneider Schmidt, Mary F. Mahon, Nasir A. Rajabi, Udo Radius, Stuart MacGregor, Maximilian W. Kuntze-Fechner, Thomas Zell, Harry Grieve, David Schmidt, John P. Lowe, and Connie J. Isaac
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Ligand ,Organic Chemistry ,Substituent ,chemistry.chemical_element ,General Chemistry ,Medicinal chemistry ,Catalysis ,Adduct ,chemistry.chemical_compound ,Nickel ,chemistry ,Diphosphines ,Moiety ,Carbene ,Phosphine - Abstract
The addition of PPh2 H, PPhMeH, PPhH2 , P(para-Tol)H2 , PMesH2 and PH3 to the two-coordinate Ni0 N-heterocyclic carbene species [Ni(NHC)2 ] (NHC=IiPr2 , IMe4 , IEt2 Me2 ) affords a series of mononuclear, terminal phosphido nickel complexes. Structural characterisation of nine of these compounds shows that they have unusual trans [H-Ni-PR2 ] or novel trans [R2 P-Ni-PR2 ] geometries. The bis-phosphido complexes are more accessible when smaller NHCs (IMe4 >IEt2 Me2 >IiPr2 ) and phosphines are employed. P-P activation of the diphosphines R2 P-PR2 (R2 =Ph2 , PhMe) provides an alternative route to some of the [Ni(NHC)2 (PR2 )2 ] complexes. DFT calculations capture these trends with P-H bond activation proceeding from unconventional phosphine adducts in which the H substituent bridges the Ni-P bond. P-P bond activation from [Ni(NHC)2 (Ph2 P-PPh2 )] adducts proceeds with computed barriers below 10 kcal mol-1 . The ability of the [Ni(NHC)2 ] moiety to afford isolable terminal phosphido products reflects the stability of the Ni-NHC bond that prevents ligand dissociation and onward reaction.
- Published
- 2021
18. Front Cover: (Z. Anorg. Allg. Chem. 17/2022)
- Author
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Udo Radius and Stefanie Dehnen
- Subjects
Inorganic Chemistry - Published
- 2022
19. N ‐Heterocyclic Carbene and Cyclic (Alkyl)(amino)carbene Adducts of Germanium(IV) and Tin(IV) Chlorides and Organyl Chlorides
- Author
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Michael S. M. Philipp, Rüdiger Bertermann, and Udo Radius
- Subjects
Inorganic Chemistry ,ddc:540 - Abstract
A study on the reactivity of N‐heterocyclic carbenes (NHCs) and the cyclic (alkyl)(amino)carbene cAAC\(^{Me}\) with selected germanium(IV) and tin(IV) chlorides and organyl chlorides is presented. The reactions of the NHCs Me\(_{2}\)Im\(^{Me}\), iPr\(_{2}\)Im\(^{Me}\) and Dipp2Im with the methyl chlorides ECl\(_{2}\)Me\(_{2}\) afforded the adducts NHC ⋅ ECl\(_{2}\)Me\(_{2}\) (E=Ge (1), Sn (2)), NHC=Me\(_{2}\)Im\(^{Me}\) (a), iPr\(_{2}\)Im\(^{Me}\) (b), Dipp\(_{2}\)Im (c)). The reaction of Me2Im\(^{Me}\) with GeCl\(_{4}\) led to isolation of Me\(_{2}\)Im\(^{Me}\) ⋅ GeCl\(_{4}\) (3), the reaction of iPr\(_{2}\)Im\(^{Me}\) with SnCl\(_{4}\) in THF afforded the THF adduct iPr\(_{2}\)Im\(^{Me}\) ⋅ SnCl\(_{4}\) ⋅ THF (4). Dipp\(_{2}\)Im ⋅ GeCl\(_{2}\)Me\(_{2}\) (1 c) isomerized into the backbone coordinated imidazolium salt [aDipp\(_{2}\)Im ⋅ GeClMe\(_{2}\)][Cl] (5) upon thermal treatment. The reactions of cAAC\(^{Me}\) with (i) ECl\(_{2}\)R\(_{2}\) (E=Ge, Sn) gave the adducts cAAC\(^{Me}\) ⋅ ECl\(_{2}\)R\(_{2}\) (R=Me: E=Ge (6); Sn (7); Ph: E=Ge (8)), with (ii) GeClMe\(_{3}\) and GeCl\(_{4}\) the salts [cAAC\(^{Me}\) ⋅ GeMe\(_{3}\)][Cl] (9) and [cAACMeCl][GeCl\(_{3}\)] (10), and (iii) with SnCl\(_{4}\) the salt [cAACMeCl][SnCl\(_{3}\)] (11) and the adduct cAAC\(^{Me}\) ⋅ SnCl\(_{4}\) (12). Reduction of 2 a with KC\(_{8}\) afforded the NHC‐stabilized stannylene Me\(_{2}\)Im\(^{Me}\) ⋅ SnMe\(_{2}\) 13, reduction of 7 with either KC8 or 1,4‐bis‐(trimethylsilyl)‐1,4‐dihydropyrazin in the presence of SnCl\(_{2}\)Me\(_{2}\) yielded cAAC\(^{Me}\) ⋅ SnMe\(_{2}\) ⋅ SnMe\(_{2}\)Cl\(_{2}\) (14).
- Published
- 2022
20. Activation of Ge-H and Sn-H Bonds with N-Heterocyclic Carbenes and a Cyclic (Alkyl)(amino)carbene
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Michael S. M. Philipp, Rüdiger Bertermann, and Udo Radius
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ddc:540 ,Organic Chemistry ,General Chemistry ,Catalysis - Abstract
A study of the reactivity of several N‐heterocyclic carbenes (NHCs) and the cyclic (alkyl)(amino)carbene 1‐(2,6‐di‐iso‐propylphenyl)‐3,3,5,5‐tetramethyl‐pyrrolidin‐2‐ylidene (cAAC\(^{Me}\)) with the group 14 hydrides GeH2Mes2 and SnH2Me2 (Me=CH\(_{3}\), Mes=1,3,5‐(CH\(_{3}\))\(_{3}\)C\(_{6}\)H\(_{2}\)) is presented. The reaction of GeH\(_{2}\)Mes\(_{2}\) with cAAC\(^{Me}\) led to the insertion of cAAC\(^{Me}\) into one Ge−H bond to give cAAC\(^{Me}\)H−GeHMes\(_{2}\) (1). If 1,3,4,5‐tetramethyl‐imidazolin‐2‐ylidene (Me\(_{2}\)Im\(^{Me}\)) was used as the carbene, NHC‐mediated dehydrogenative coupling occurred, which led to the NHC‐stabilized germylene Me\(_{2}\)Im\(^{Me}\)⋅GeMes\(_{2}\) (2). The reaction of SnH\(_{2}\)Me\(_{2}\) with cAAC\(^{Me}\) also afforded the insertion product cAAC\(^{Me}\)H−SnHMe\(_{2}\) (3), and reaction of two equivalents Me\(_{2}\)Im\(^{Me}\) with SnH\(_{2}\)Me\(_{2}\) gave the NHC‐stabilized stannylene Me\(_{2}\)Im\(^{Me}\)⋅SnMe\(_{2}\) (4). If the sterically more demanding NHCs Me\(_{2}\)Im\(^{Me}\), 1,3‐di‐isopropyl‐4,5‐dimethyl‐imidazolin‐2‐ylidene (iPr\(_{2}\)Im\(^{Me}\)) and 1,3‐bis‐(2,6‐di‐isopropylphenyl)‐imidazolin‐2‐ylidene (Dipp\(_{2}\)Im) were employed, selective formation of cyclic oligomers (SnMe\(_{2}\))\(_{n}\) (5; n=5–8) in high yield was observed. These cyclic oligomers were also obtained from the controlled decomposition of cAAC\(^{Me}\)H−SnHMe\(_{2}\) (3).
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- 2022
21. Transition Metal Catalyst‐Free, Base‐Promoted 1,2‐Additions of Polyfluorophenylboronates to Aldehydes and Ketones
- Author
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Todd B. Marder, Xiaoling Luo, Udo Radius, Goutam Kumar Kole, Alexandra Friedrich, Zhiqiang Liu, Yudha P. Budiman, Ya-Ming Tian, and Stephen A. Westcott
- Subjects
Base (chemistry) ,chemistry.chemical_element ,Alcohol ,010402 general chemistry ,01 natural sciences ,Catalysis ,chemistry.chemical_compound ,Transition metal ,1,2‐Additions ,fluoroarene ,Organic chemistry ,Research Articles ,chemistry.chemical_classification ,010405 organic chemistry ,Hydrogen bond ,Chemistry ,alcohol ,Free base ,General Chemistry ,General Medicine ,0104 chemical sciences ,transition metal-free ,1,2-addition reaction ,Fluorine ,Counterion ,ddc:546 ,Research Article ,boronate esters - Abstract
A novel protocol for the transition metal‐free 1,2‐addition of polyfluoroaryl boronate esters to aldehydes and ketones is reported, which provides secondary alcohols, tertiary alcohols, and ketones. Control experiments and DFT calculations indicate that both the ortho‐F substituents on the polyfluorophenyl boronates and the counterion K+ in the carbonate base are critical. The distinguishing features of this procedure include the employment of commercially available starting materials and the broad scope of the reaction with a wide variety of carbonyl compounds giving moderate to excellent yields. Intriguing structural features involving O−H⋅⋅⋅O and O−H⋅⋅⋅N hydrogen bonding, as well as arene‐perfluoroarene interactions, in this series of racemic polyfluoroaryl carbinols have also been addressed., Herein we report a transition metal‐free procedure for the base‐promoted 1,2‐addition of polyfluorophenylboronates to aldehydes and ketones to generate organofluorine‐containing alcohols in yields up to 93 %.
- Published
- 2021
22. Das 1,3‐Bis(tricyanoboran)imidazolin‐2‐ylidenat‐Anion – Ein ditopischer dianionischer N‐heterocyclischer Carben‐Ligand
- Author
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Ludwig Zapf, Udo Radius, and Maik Finze
- Subjects
General Medicine - Published
- 2021
23. 1,3‐Bis(tricyanoborane)imidazoline‐2‐ylidenate Anion—A Ditopic Dianionic N‐Heterocyclic Carbene Ligand
- Author
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Maik Finze, Udo Radius, and Ludwig Zapf
- Subjects
Steric effects ,Carbenes | Hot Paper ,chemistry.chemical_element ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Catalysis ,Adduct ,chemistry.chemical_compound ,Imidazolate ,Pyridine ,cyanoborate ,Research Articles ,010405 organic chemistry ,Ligand ,General Chemistry ,0104 chemical sciences ,Nickel ,anionic carbene ,chemistry ,boron ,ddc:546 ,N-heterocyclic carbene ,Carbene ,imidazolate ,Research Article ,Methyl iodide - Abstract
The 1,3‐bis(tricyanoborane)imidazolate anion 1 was obtained in high yield from lithium imidazolate and B(CN)3−pyridine adduct. Anion 1 is chemically very robust and thus allowed the isolation of the corresponding H5O2 + salt. Furthermore, monoanion 1 served as starting species for the novel dianionic N‐heterocyclic carbene (NHC), 1,3‐bis(tricyanoborane)imidazoline‐2‐ylidenate anion 3 that acts as ditopic ligand via the carbene center and the cyano groups at boron. First reactions of this new NHC 3 with methyl iodide, elemental selenium, and [Ni(CO)4] led to the methylated imidazolate ion 4, the dianionic selenium adduct 5, and the dianionic nickel tricarbonyl complex 6. These NHC derivatives provide a first insight into the electronic and steric properties of the dianionic NHC 3. Especially the combination of properties, such as double negative charge, different coordination sites, large buried volume and good σ‐donor and π‐acceptor ability, make NHC 3 a unique and promising ligand and building block., Unprecedentedly stable salts of the 1,3‐bis(tricyanoborane)imidazolate ion with different types of counterions were obtained on large scale. Deprotonation of the imidazolate ion provided access to the corresponding dianionic NHC that acts as ditopic ligand.
- Published
- 2021
24. Ni‐Catalyzed Borylation of Aryl Sulfoxides
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Mingming Huang, Todd B. Marder, Zhu Wu, Udo Radius, Alexandra Friedrich, Xiaoling Luo, Johannes Krebs, and Stephen A. Westcott
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Substituent ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Borylation ,Catalysis ,chemistry.chemical_compound ,nickel ,borylation ,cross-coupling ,N-heterocyclic carbenes ,Boron ,Trifluoromethyl ,Full Paper ,010405 organic chemistry ,Aryl ,Organic Chemistry ,Regioselectivity ,Sulfoxide ,General Chemistry ,Full Papers ,Oxidative addition ,0104 chemical sciences ,chemistry ,ddc:546 ,Carbene - Abstract
A nickel/N‐heterocyclic carbene (NHC) catalytic system has been developed for the borylation of aryl sulfoxides with B2(neop)2 (neop=neopentyl glycolato). A wide range of aryl sulfoxides with different electronic and steric properties were converted into the corresponding arylboronic esters in good yields. The regioselective borylation of unsymmetric diaryl sulfoxides was also feasible leading to borylation of the sterically less encumbered aryl substituent. Competition experiments demonstrated that an electron‐deficient aryl moiety reacts preferentially. The origin of the selectivity in the Ni‐catalyzed borylation of electronically biased unsymmetrical diaryl sulfoxide lies in the oxidative addition step of the catalytic cycle, as oxidative addition of methoxyphenyl 4‐(trifluoromethyl)phenyl sulfoxide to the Ni(0) complex occurs selectively to give the structurally characterized complex trans‐[Ni(ICy)2(4‐CF3‐C6H4){(SO)‐4‐MeO‐C6H4}] 4. For complex 5, the isomer trans‐[Ni(ICy)2(C6H5)(OSC6H5)] 5‐I was structurally characterized in which the phenyl sulfinyl ligand is bound via the oxygen atom to nickel. In solution, the complex trans‐[Ni(ICy)2(C6H5)(OSC6H5)] 5‐I is in equilibrium with the S‐bonded isomer trans‐[Ni(ICy)2(C6H5)(SOC6H5)] 5, as shown by NMR spectroscopy. DFT calculations reveal that these isomers are separated by a mere 0.3 kJ/mol (M06/def2‐TZVP‐level of theory) and connected via a transition state trans‐[Ni(ICy)2(C6H5)(η2‐{SO}‐C6H5)], which lies only 10.8 kcal/mol above 5., A nickel/N‐heterocyclic carbene (NHC) catalytic system has been developed for the borylation of aryl sulfoxides with B2(neop)2 (neop=neopentyl glycolato). A wide range of aryl sulfoxides with different electronic and steric properties were converted into the corresponding arylboronic esters in good yields. Elucidation of key mechanistic features of this newly developed reaction led to the identification of fully characterized nickel intermediates.
- Published
- 2021
25. Tricyanoborane‐Functionalized Anionic N‐Heterocyclic Carbenes: Adjustment of Charge and Stereo‐Electronic Properties
- Author
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Ludwig Zapf, Sven Peters, Rüdiger Bertermann, Udo Radius, and Maik Finze
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ddc:540 ,Organic Chemistry ,General Chemistry ,Catalysis - Abstract
The 1‐methyl‐3‐(tricyanoborane)imidazolin‐2‐ylidenate anion (2) was obtained in high yield by deprotonation of the B(CN)3‐methylimidazole adduct 1. Regarding charge and stereo‐electronic properties, anion 2 closes the gap between well‐known neutral NHCs and the ditopic dianionic NHC, the 1,3‐bis(tricyanoborane)imidazolin‐2‐ylidenate dianion (IIb). The influence of the number of N‐bonded tricyanoborane moieties on the σ‐donating and π‐accepting properties of NHCs was assessed by quantum chemical calculations and verified by experimental data on 2, IIb, and 1,3‐dimethylimidazolin‐2‐ylidene (IMe, IIa). Therefore NHC 2, which acts as a ditopic ligand via the carbene center and the cyano groups, was reacted with alkyl iodides, selenium, and [Ni(CO)\(_{4}\)] yielding alkylated imidazoles 3 and 4, the anionic selenium adduct 5, and the anionic nickel tricarbonyl complex 8, respectively. The results of this study prove that charge, number of coordination sites, buried volume (%V\(_{bur}\)) and σ‐donor and π‐acceptor abilities of NHCs can be effectively fine‐tuned via the number of tricyanoborane substituents.
- Published
- 2022
26. Visible-light-driven graphene supported Cu/Pd alloy nanoparticle-catalyzed borylation of alkyl bromides and chlorides in air
- Author
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Ya-Ming Tian, Todd B. Marder, Zhi-Feng Jiao, Udo Radius, Xiao-Ning Guo, Holger Braunschweig, and Xiang-Yun Guo
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chemistry.chemical_classification ,010405 organic chemistry ,Chemistry ,Graphene ,Halide ,010402 general chemistry ,Photochemistry ,Heterogeneous catalysis ,01 natural sciences ,Borylation ,Catalysis ,0104 chemical sciences ,law.invention ,law ,Electrophile ,Photocatalysis ,Physical and Theoretical Chemistry ,Alkyl - Abstract
A highly efficient photocatalytic protocol for borylation of alkyl bromides and chlorides with graphene supported Cu/Pd alloy nanoparticles as a heterogeneous catalyst is reported. This photocatalytic system operates with visible light in air, providing a wide range of primary and secondary alkyl halides with B2pin2 or B2neop2 in high yields at low temperatures, thereby demonstrating its broad utility and functional group tolerance. The high performance is attributed to a synergistic effect of localized surface plasmon resonance (LSPR) of Cu and charge transfer from Cu to Pd due to the alloy surface charge heterogeneity. Transfer of energetic electrons from Pd to electrophilic alkyl halides lead to the formation of the alkyl radicals, which quickly react with a nucleophilic adduct of a diboron compound with base adsorbed on the positively charged Cu sites to form the corresponding borylation product.
- Published
- 2021
27. A General Synthetic Route to NHC‐Phosphinidenes: NHC‐mediated Dehydrogenation of Primary Phosphines
- Author
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Katharina Lubitz, Michael Philipp, Günther Horrer, Luis Werner, Udo Radius, and Maximilian W. Kuntze-Fechner
- Subjects
Inorganic Chemistry ,Primary (chemistry) ,Chemistry ,Dehydrogenation ,ddc:546 ,Medicinal chemistry - Abstract
The dehydrocoupling of primary phosphines with N-heterocyclic carbenes (NHCs) to yield NHC-phosphinidenes is reported. The reaction of two equivalents of the NHCs Me\(_2\)Im (1,3-dimethylimidazolin-2-ylidene), Me\(_4\)Im (1,3,4,5-tetramethylimidazolin-2-ylidene), iPr\(_2\)Im (1,3-di-iso-propylimidazolin-2-ylidene) and Mes\(_2\)Im (2,4,6-trimethylphenylimidazolin-2-ylidene) with PhPH\(_2\) and MesPH\(_2\) led to the NHC stabilized phosphinidenes (NHC)PAr: (iPr\(_2\)Im)PPh (1), (Mes\(_2\)Im)PPh (2), (Me\(_4\)Im)PPh (3), (Mes\(_2\)Im)PMes (4), (Me\(_2\)Im)PMes (5), (Me\(_4\)Im)PMes (6) and (iPr\(_2\)Im)PMes (7). The reaction of tBuPH\(_2\) with two equivalents of the NHCs afforded the corresponding NHC stabilized parent phosphinidenes (NHC)PH: (iPr\(_2\)Im)PH (8), (Mes\(_2\)Im)PH (9) and (Me\(_4\)Im)PH (10). Reaction of 1 with oxygen and sulfur led to isolation of iPr\(_2\)Im-P(O)\(_2\)Ph (11) and iPr\(_2\)Im-P(S)\(_2\)Ph (12), whereas the reaction with elemental selenium and tellurium gave (NHC)PPh cleavage with formation of (iPr\(_2\)Im)Se (13), iPr\(_2\)ImTe (14) and different cyclo-oligophosphines. Furthermore, the complexes [{(iPr\(_2\)Im)PPh}W(CO)\(_5\)] (15), [Co(CO)\(_2\)(NO){(iPr\(_2\)Im)PPh}] (16) and [(η\(^5\)-C\(_5\)Me\(_2\))Co(η\(^2\)-C\(_2\)H\(_4\)){(iPr\(_2\)Im)PPh}] (17) have been prepared starting from 1 and a suitable transition metal complex precursor. The complexes 16 and 17 decompose in solution upon heating to ca. 80 °C to yield the NHC complexes [Co(iPr\(_2\)Im)(CO)\(_2\)(NO)] and [(η\(^5\)-C\(_5\)Me\(_5\))Co(iPr\(_2\)Im)(η\(^2\)-C\(_2\)H\(_4\))] with formation of cyclo-oligophosphines. The reaction of 1 with [Ni(COD)\(_2\)] afforded the diphosphene complex [Ni(iPr\(_2\)Im)\(_2\)(trans-PhP=PPh)] 18.
- Published
- 2021
28. Photoinduced Borylation for the Synthesis of Organoboron Compounds
- Author
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Holger Braunschweig, Todd B. Marder, Udo Radius, Ya-Ming Tian, and Xiao-Ning Guo
- Subjects
chemistry.chemical_classification ,Reaction mechanism ,010405 organic chemistry ,Chemistry ,Aryl ,Halide ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Combinatorial chemistry ,Borylation ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,Transition metal ,Organocatalysis ,Alkyl - Abstract
Organoboron compounds have important synthetic value and can be applied in numerous transformations. The development of practical and convenient ways to synthesize boronate esters has thus attracted significant interest. Photoinduced borylations originated from stoichiometric reactions of alkanes and arenes with well-defined metal-boryl complexes. Now, photoredox-initiated borylations, catalyzed by either transition metal or organic photocatalysts, and photochemical borylations with high efficiency have become a burgeoning area of research. In this Focus Review, we summarize research on photoinduced borylations, especially emphasizing recent developments and trends. This includes the photoinduced borylation of arenes, alkanes, aryl/alkyl halides, activated carboxylic acids, amines, alcohols, and so on based on transition metal catalysis, metal-free organocatalysis, and direct photochemical activation. We focus on reaction mechanisms involving single-electron transfer, triplet-energy transfer, and other radical processes.
- Published
- 2021
29. Fluorinated Aryl Boronates as Building Blocks in Organic Synthesis
- Author
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Todd B. Marder, Udo Radius, Stephen A. Westcott, and Yudha P. Budiman
- Subjects
chemistry.chemical_compound ,chemistry ,Aryl ,ddc:540 ,Fluorine ,chemistry.chemical_element ,Organic chemistry ,Homogeneous catalysis ,Organic synthesis ,General Chemistry - Abstract
Organoboron compounds are well known building blocks for many organic reactions. However, under basic conditions, polyfluorinated aryl boronic acid derivatives suffer from instability issues that are accelerated in compounds containing an ortho‐fluorine group, which result in the formation of the corresponding protodeboronation products. Therefore, a considerable amount of research has focused on novel methodologies to synthesize these valuable compounds while avoiding the protodeboronation issue. This review summarizes the latest developments in the synthesis of fluorinated aryl boronic acid derivatives and their applications in cross‐coupling reactions and other transformations. image
- Published
- 2021
30. C–F bond activation of perfluorinated arenes using NHC-stabilized cobalt half-sandwich complexes
- Author
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Katharina Lubitz, Daniel Ertler, Simon Dürr, Maximilian W. Kuntze-Fechner, and Udo Radius
- Subjects
chemistry.chemical_classification ,Olefin fiber ,Alkene ,Ligand ,chemistry.chemical_element ,Hexafluorobenzene ,General Chemistry ,Medicinal chemistry ,Oxidative addition ,Catalysis ,chemistry.chemical_compound ,chemistry ,Side product ,Materials Chemistry ,Reactivity (chemistry) ,Cobalt - Abstract
A study on the reactivity of NHC cobalt half-sandwich complexes [(η5-C5R15)Co(R22Im)(η2-C2H4)] (R1 = H; R2 = Me 1, iPr 2) and [(η5-C5R15)Co(R22Im)(η2-C2H3{SiMe3})] (R1 = H, R2 = Me 3, iPr 4; R1 = Me, R2 = Me 5, iPr 6) towards selected perfluoroarenes is presented (R2Im = 1,3-di(organyl)-imidazolin-2-ylidene). The reaction with hexafluorobenzene, perfluorotoluene and decafluorobiphenyl at 100 °C led to the isolation of the cobalt(II) complexes [CpCo(iPr2Im)(C6F5)] 7, [CpCo(iPr2Im)(C7F7)] 8, [CpCo(iPr2Im)(C12F9)] 9, [Cp*Co(iPr2Im)(C6F5)] 10, [Cp*Co(iPr2Im)(C7F7)] 11 and [Cp*Co(iPr2Im)(C12F9)] 12 (Cp* = η5-C5{CH3}5), Cp = η5-C5H5). The cobalt(II) fluoride [CpCo(iPr2Im)(F)] was detected as a side product of these reactions. The reaction of [CpCo(R22Im)(η2-C2H4)] (R2 = Me 1, iPr 2) with C6F6 and C7F8 at 60 °C afforded the dinuclear complexes [{CpCo(R22Im)}2(μ-η2,η2-C6F6)] (R2 = Me 13, iPr 14) and [{CpCo(R22Im)}2(μ-η2,η2-C7F8)] (R2 = Me 15, iPr 16). Furthermore, the dinuclear complexes [{CpCo(Me2Im)}2(μ-η2,η2-C10F8)] 17, [{CpCo(iPr2Im)}2(μ-η2,η2-C10F8)] 18 and mononuclear [CpCo(iPr2Im)(η2-C10F8)] 19 were isolated from the reaction of 1 and 2 with octafluoronaphthalene at room temperature. Based on the experimental data a mechanism is proposed for the C–F bond activation of perfluoroarenes with complexes [Cp(*)Co(NHC)(olefin)]. Transfer of [Cp(*)Co(NHC)] to the perfluoroarene, which is limited by the activation barrier to replace the alkene ligand, affords mononuclear cobalt complexes [Cp(*)Co(NHC)(η2-ArF)]. Ligand dismutation at higher temperatures leads to dinuclear complexes [{Cp(*)Co(NHC)}2(μ-η2,η2-ArF)], which are precursors for the formation of the cobalt(II) complexes [Cp(*)Co(NHC)(ArF)] and [Cp(*)Co(NHC)(F)]. One electron oxidative addition prevails in the C–F bond activation step using these cobalt half-sandwich complexes.
- Published
- 2021
31. N-Heterocyclic silylenes as ambiphilic activators and ligands
- Author
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Mirjam J. Krahfuss and Udo Radius
- Subjects
Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Polymer chemistry ,Orbital region ,Ring (chemistry) ,Carbene ,Organometallic chemistry ,Phosphine ,Catalysis - Abstract
This frontiers article highlights recent developments of the use of N-heterocyclic silylenes (NHSis), the higher homologues of the Arduengo-carbenes, as ambiphilic activators and ligands in organometallic chemistry and provides a comparison of five-membered ring NHSi ligands with ubiquitous N-heterocyclic carbene (NHC) and phosphine ligands. The frontier orbital region of NHSis differs considerably from that of NHCs which results in different ligation properties. The donor properties of NHSis are closer to those of phosphines than to those of NHCs. NHSis reveal a much stronger tendency to act as bridging ligands between two metal centres than NHCs or phosphines and NHSi insertion reactions into metal-ligand bonds are more facile to achieve compared to similar insertion reactions of NHCs. These interesting properties clearly distinguish NHSi ligands from their NHC or phosphine counterparts and should provide novel reactivities in basic organometallic chemistry and catalysis.
- Published
- 2021
32. Anorganische Chemie: Prinzipien von Struktur und Reaktivität
- Author
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James Huheey, Ellen Keiter, Richard Keiter, Ralf Steudel, Frank Breher, Maik Finze, Dirk Johrendt, Martin Kaupp, Hans-Joachim Lunk, Udo Radius, Ulrich Schatzschneider and James Huheey, Ellen Keiter, Richard Keiter, Ralf Steudel, Frank Breher, Maik Finze, Dirk Johrendt, Martin Kaupp, Hans-Joachim Lunk, Udo Radius, Ulrich Schatzschneider
- Published
- 2014
33. Copper‐Catalyzed Oxidative Cross‐Coupling of Electron‐Deficient Polyfluorophenylboronate Esters with Terminal Alkynes
- Author
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Alexandra Friedrich, Todd B. Marder, Mingming Huang, Udo Radius, Zhiqiang Liu, Stephen A. Westcott, Ya-Ming Tian, and Yudha P. Budiman
- Subjects
fluoroarenes ,chemistry.chemical_element ,Sonogashira coupling ,Oxidative phosphorylation ,coupling reactions ,010402 general chemistry ,01 natural sciences ,Catalysis ,Coupling reaction ,chemistry.chemical_compound ,Full Paper ,010405 organic chemistry ,Organic Chemistry ,Substrate (chemistry) ,Fluorine ,General Chemistry ,Full Papers ,Combinatorial chemistry ,0104 chemical sciences ,Coupling (electronics) ,chemistry ,Terminal (electronics) ,ddc:540 ,Functional group ,Sonogashira reaction ,boronate esters - Abstract
We report herein a mild procedure for the copper‐catalyzed oxidative cross‐coupling of electron‐deficient polyfluorophenylboronate esters with terminal alkynes. This method displays good functional group tolerance and broad substrate scope, generating cross‐coupled alkynyl(fluoro)arene products in moderate to excellent yields. Thus, it represents a simple alternative to the conventional Sonogashira reaction., BFF: A mild procedure is reported for the synthesis of alkynyl(fluoro)arenes via copper‐catalyzed oxidative cross‐coupling of polyfluorophenylboronate esters with terminal alkynes.
- Published
- 2020
34. Visible-Light-Induced Ni-Catalyzed Radical Borylation of Chloroarenes
- Author
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Jörn Nitsch, Ya-Ming Tian, Xiao-Ning Guo, Ivo Krummenacher, Todd B. Marder, Udo Radius, Holger Braunschweig, and Zhu Wu
- Subjects
General Chemistry ,010402 general chemistry ,Highly selective ,Photochemistry ,01 natural sciences ,Biochemistry ,Borylation ,Catalysis ,0104 chemical sciences ,IMes ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,chemistry ,Visible spectrum - Abstract
A highly selective and general photoinduced C–Cl borylation protocol that employs [Ni(IMes)2] (IMes = 1,3-dimesitylimidazoline-2-ylidene) for the radical borylation of chloroarenes is reported. Thi...
- Published
- 2020
35. Selective, Transition Metal-free 1,2-Diboration of Alkyl Halides, Tosylates, and Alcohols
- Author
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Mingming Huang, Jiefeng Hu, Shasha Shi, Alexandra Friedrich, Johannes Krebs, Stephen A. Westcott, Udo Radius, and Todd B. Marder
- Subjects
Inorganic Chemicals ,Alcohols ,Organic Chemistry ,Transition Elements ,Esters ,General Chemistry ,Chemistry Techniques, Synthetic ,Alkenes ,ddc:546 ,Catalysis - Abstract
Defunctionalization of readily available feedstocks to provide alkenes for the synthesis of multifunctional molecules represents an extremely useful process in organic synthesis. Herein, we describe a transition metal-free, simple and efficient strategy to access alkyl 1,2-bis(boronate esters) via regio- and diastereoselective diboration of secondary and tertiary alkyl halides (Br, Cl, I), tosylates, and alcohols. Control experiments demonstrated that the key to this high reactivity and selectivity is the addition of a combination of potassium iodide and N,N-dimethylacetamide (DMA). The practicality and industrial potential of this transformation are demonstrated by its operational simplicity, wide functional group tolerance, and the late-stage modification of complex molecules. From a drug discovery perspective, this synthetic method offers control of the position of diversification and diastereoselectivity in complex ring scaffolds, which would be especially useful in a lead optimization program.
- Published
- 2022
36. Cationic Nickel d\(^{9}\)‐Metalloradicals [Ni(NHC)\(_{2}\)]\(^{+}\)
- Author
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Lukas Tendera, Martin S. Luff, Ivo Krummenacher, and Udo Radius
- Subjects
Inorganic Chemistry ,ddc:540 - Abstract
A series of five new homoleptic, linear nickel d\(^{9}\)‐complexes of the type [Ni\(^{I}\)(NHC)\(_{2}\)]\(^{+}\) is reported. Starting from the literature known Ni(0) complexes [Ni(Mes\(_{2}\)Im)\(_{2}\)] 1, [Ni(Mes\(_{2}\)Im\(^{H2}\))2] 2, [Ni(Dipp\(_{2}\)Im)\(_{2}\)] 3, [Ni(Dipp\(_{2}\)Im\(^{H2}\))\(_{2}\)] 4 and [Ni(cAAC\(^{Me}\))\(_{2}\)] 5 (Mes\(_{2}\)Im=1,3‐bis(2,4,6‐trimethylphenyl)‐imidazolin‐2‐ylidene, Mes\(_{2}\)Im\(^{H2}\)=1,3‐bis(2,4,6‐trimethylphenyl)‐imidazolidin‐2‐ylidene, Dipp\(_{2}\)Im=1,3‐bis(2,6‐diisopropylphenyl)‐imidazolin‐2‐ylidene, Dipp\(_{2}\)Im\(^{H2}\)=1,3‐bis(2,6‐diisopropylphenyl)‐imidazolidin‐2‐ylidene, cAAC\(^{Me}\)=1‐(2,6‐diisopropylphenyl)‐3,3,5,5‐tetramethylpyrrolidin‐2‐yliden), their oxidized Ni(I) analogues [Ni\(^{I}\)(Mes\(_{2}\)Im)\(_{2}\)][BPh\(_{4}\)] 1\(^{+}\), [Ni\(^{I}\)(Mes\(_{2}\)Im\(^{H2}\))\(_{2}\)][BPh\(_{4}\)] 2\(^{+}\), [Ni\(^{I}\)(Dipp\(_{2}\)Im)\(_{2}\)][BPh\(_{4}\)] 3\(^{+}\), [Ni\(^{I}\)(Dipp\(_{2}\)Im\(^{H2}\))\(_{2}\)][BPh\(_{4}\)] 4\(^{+}\) and [Ni\(^{I}\)(cAAC\(^{Me}\))\(_{2}\)][BPh\(_{4}\)] 5\(^{+}\) were synthesized by one‐electron oxidation with ferrocenium tetraphenyl‐borate. The complexes 1\(^{+}\)–5\(^{+}\) were fully characterized including X‐ray structure analysis. The complex cations reveal linear geometries in the solid state and NMR spectra with extremely broad, paramagnetically shifted resonances. DFT calculations predicted an orbitally degenerate ground state leading to large magnetic anisotropy, which was verified by EPR measurements in solution and on solid samples. The magnetic anisotropy of the complexes is highly dependent from the steric protection of the metal atom, which results in a noticeable decrease of the g‐tensor anisotropy for the N‐Mes substituted complexes 1\(^{+}\) and 2\(^{+}\) in solution due to the formation of T‐shaped THF adducts.
- Published
- 2022
37. Transition Metal‐Free Regio‐ and Stereo‐Selective trans Hydroboration of 1,3‐Diynes: A Phosphine‐Catalyzed Access to (E)‐1‐Boryl‐1,3‐Enynes
- Author
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Swetha Jos, Connor Szwetkowski, Carla Slebodnick, Robert Ricker, Ka Lok Chan, Wing Chun Chan, Udo Radius, Zhenyang Lin, Todd B. Marder, and Webster L. Santos
- Subjects
Organic Chemistry ,ddc:540 ,General Chemistry ,Catalysis - Abstract
We report a transition metal-free, regio- and stereo-selective, phosphine-catalyzed method for the trans hydroboration of 1,3-diynes with pinacolborane that affords (E)-1-boryl-1,3-enynes. The reaction proceeds with excellent selectivity for boron addition to the external carbon of the 1,3-diyne framework as unambiguously established by NMR and X-ray crystallographic studies. The reaction displays a broad substrate scope including unsymmetrical diynes to generate products in high yield (up to 95 %). Experimental and theoretical studies suggest that phosphine attack on the alkyne is a key process in the catalytic cycle.
- Published
- 2022
38. A Versatile Route To Cyclic (Alkyl)(Amino)Carbene–Stabilized Stibinidenes
- Author
-
Michael S. M. Philipp and Udo Radius
- Subjects
Inorganic Chemistry ,ddc:546 - Abstract
A convenient route for the synthesis of the cAAC\(^{Me}\) (cAAC=cyclic (alkyl)(amino)carbene, cAAC\(^{Me}\)=1-(2,6-di-iso-propylphenyl)-3,3,5,5-tetramethyl-pyrrolidin-2-ylidene) and cAAC\(^{Cy}\) (cAAC\(^{Cy}\)=2-azaspiro[4.5]dec-2-(2,6-diisopropylphenyl)-3,3-dimethyl-1-ylidene) stabilized stibinidenes cAAC\(^{Me}\)⋅SbMes (2a) (Mes=2,4,6-trimethylphenyl) and cAAC\(^{Cy}\)⋅SbMes (2b) is reported. A mechanism for the formation of [cAAC\(^{R}\)Cl][SbCl\(_{3}\)Mes] 1 and cAAC\(^{R}\)⋅SbMes 2 from the reaction of cAAC with the antimony(III) precursor SbCl\(_{2}\)Mes, which proceeds via the isolable intermediate [cAAC\(^{R}\)SbClMes][SbCl\(_{3}\)Mes] (3), is proposed.
- Published
- 2022
39. High photocatalytic activity of a NiO nanodot-decorated Pd/SiC catalyst for the Suzuki-Miyaura cross-coupling of aryl bromides and chlorides in air under visible light
- Author
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Zhi-Feng Jiao, Xiang-Yun Guo, Xiao-Ning Guo, Ying-Xiong Wang, Cai-Hong Hao, Yan Qiao, Bin Zhang, Todd B. Marder, Yong Qin, Udo Radius, Holger Braunschweig, and Ya-Ming Tian
- Subjects
010405 organic chemistry ,Aryl ,Non-blocking I/O ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Electron transfer ,Atomic layer deposition ,chemistry.chemical_compound ,chemistry ,Photocatalysis ,Nanodot ,Physical and Theoretical Chemistry ,Phenylboronic acid - Abstract
The Suzuki-Miyaura cross-coupling reaction is an effective process for C-C bond formation in organic synthesis. Herein, we report a NiO nanodot-decorated Pd/SiC catalyst, synthesized by atomic layer deposition, which shows high photocatalytic activity for the Suzuki-Miyaura coupling of both aryl bromides and chlorides with phenylboronic acid at 30 °C in air. The Mott-Schottky contact in SiC/Pd enhances the rapid transfer of the photogenerated electrons from SiC to Pd nanoparticles. Moreover, the energy different between the highest occupied molecular orbital of the ultrafine NiO nanodots and the Fermi level of Pd forces a spontaneous electron transfer from NiO to Pd. As a result, the concentrated electrons in the Pd nanoparticles can facilitate the cleavage of C-Br or C-Cl bonds, which normally requires rather high temperatures in thermal processes. The holes left on the SiC support can assist the cleavage of the C-B bond.
- Published
- 2020
40. N-Heterocyclic Silylenes as Ligands in Transition Metal Carbonyl Chemistry
- Author
-
Jörn Nitsch, F. Matthias Bickelhaupt, Mirjam J. Krahfuß, Todd B. Marder, Udo Radius, Chemistry and Pharmaceutical Sciences, and AIMMS
- Subjects
Orbital region ,010402 general chemistry ,01 natural sciences ,Catalysis ,Coordination complex ,transition metal complexes ,Silicon Chemistry ,chemistry.chemical_compound ,Transition metal ,silylene complexes ,Reactivity (chemistry) ,N-heterocyclic carbenes ,Theoretical Chemistry ,silylenes ,chemistry.chemical_classification ,Full Paper ,010405 organic chemistry ,Bond strength ,Ligand ,Organic Chemistry ,Silylene ,General Chemistry ,Full Papers ,0104 chemical sciences ,Crystallography ,chemistry ,Carbene ,stereoelectronic parameters - Abstract
A study on the reactivity of the N‐heterocyclic silylene Dipp2NHSi (1,3‐bis(diisopropylphenyl)‐1,3‐diaza‐2‐silacyclopent‐4‐en‐2‐yliden) with the transition metal complexes [Ni(CO)4], [M(CO)6] (M=Cr, Mo, W), [Mn(CO)5(Br)] and [(η 5‐C5H5)Fe(CO)2(I)] is reported. We demonstrate that N‐heterocyclic silylenes, the higher homologues of the now ubiquitous NHC ligands, show a remarkably different behavior in coordination chemistry compared to NHC ligands. Calculations on the electronic features of these ligands revealed significant differences in the frontier orbital region which lead to some peculiarities of the coordination chemistry of silylenes, as demonstrated by the synthesis of the dinuclear, NHSi‐bridged complex [{Ni(CO)2(μ‐Dipp2NHSi)}2] (2), complexes [M(CO)5(Dipp2NHSi)] (M=Cr 3, Mo 4, W 5), [Mn(CO)3(Dipp2NHSi)2(Br)] (9) and [(η 5‐C5H5)Fe(CO)2(Dipp2NHSi‐I)] (10). DFT calculations on several model systems [Ni(L)], [Ni(CO)3(L)], and [W(CO)5(L)] (L=NHC, NHSi) reveal that carbenes are typically the much better donor ligands with a larger intrinsic strength of the metal–ligand bond. The decrease going from the carbene to the silylene ligand is mainly caused by favorable electrostatic contributions for the NHC ligand to the total bond strength, whereas the orbital interactions were often found to be higher for the silylene complexes. Furthermore, we have demonstrated that the contribution of σ‐ and π‐interaction depends significantly on the system under investigation. The σ‐interaction is often much weaker for the NHSi ligand compared to NHC but, interestingly, the π‐interaction prevails for many NHSi complexes. For the carbonyl complexes, the NHSi ligand is the better σ‐donor ligand, and contributions of π‐symmetry play only a minor role for the NHC and NHSi co‐ligands., A study on the reactivity of the N‐heterocyclic silylene (NHSi) Dipp2NHSi (1,3‐bis(diisopropylphenyl)‐1,3‐diaza‐2‐silacyclopent‐4‐en‐2‐yliden) with different transition metal carbonyl complexes and calculations on the electronic features of these NHSi ligands are presented and compared to NHC (N‐Heterocyclic Carbene) ligands. The reaction of Dipp2NHSi with the [Ni(CO)4], [M(CO)6] (M=Cr, Mo, W), [Mn(CO)5(Br)] and [Fe(η 5‐C5H5)(CO)2(I)] leads to the mono‐ and bis‐silylene complexes [{Ni(CO)2(μ‐Dipp2NHSi)}2] (2), [M(CO)5(Dipp2NHSi)] (M=Cr 3, Mo 4, W 5), [Mn(CO)3(NHSi)2(Br)] (9) and [(η 5‐C5H5)Fe(CO)2(Dipp2NHSi‐I)] (10).
- Published
- 2020
41. Bis‐NHC Aluminium and Gallium Dihydride Cations [(NHC) 2 EH 2 ] + (E = Al, Ga)
- Author
-
Luis Werner, Andreas Hock, Melanie Riethmann, and Udo Radius
- Subjects
Inorganic Chemistry ,Crystallography ,chemistry.chemical_compound ,chemistry ,Main group element ,Gallane ,Aluminium ,chemistry.chemical_element ,Nuclear magnetic resonance spectroscopy ,Gallium ,ddc:546 ,Methyl iodide - Abstract
The NHC alane and gallane adducts (NHC)·AlH\(_{2}\)I (NHC = Me\(_{2}\)Im\(^{Me}\) 7, iPr\(_{2}\)Im 8, iPr\(_{2}\)Im\(^{Me}\) 9) and (NHC)·GaH\(_{2}\)I (NHC = Me\(_{2}\)Im\(^{Me}\) 10, iPr\(_{2}\)Im\(^{Me}\) 11, Dipp\(_{2}\)Im 12; R\(_{2}\)Im = 1,3‐di‐organyl‐imidazolin‐2‐ylidene; Dipp = 2,6‐diisopropylphenyl; iPr = isopropyl; Me\(_{2}\)Im\(^{Me}\) = 1,3,4,5‐tetra‐methyl‐imidazolin‐2‐ylidene) were prepared either by the simple yet efficient reaction of the NHC adduct (NHC)·AlH\(_{3}\) with elemental iodine or by the treatment of (NHC)·GaH\(_{3}\) with an excess of methyl iodide at room temperature. The reaction of one equivalent of the group 13 NHC complexes with an additional equivalent of the corresponding NHC afforded cationic aluminium and gallium hydrides [(NHC)\(_{2}\)·AlH\(_{2}\)]\(^{+}\)I− (NHC = Me\(_{2}\)Im\(^{Me}\) 13, iPr\(_{2}\)Im 14, iPr\(_{2}\)Im\(^{Me}\) 15) and [(NHC)\(_{2}\)·GaH\(_{2}\)]\(^{+}\)I− (NHC = Me\(_{2}\)Im\(^{Me}\) 16, iPr\(_{2}\)Im\(^{Me}\) 17) and the normal and abnormal NHC coordinated compound [(Dipp\(_{2}\)Im)·GaH\(_{2}\)(aDipp\(_{2}\)Im)]+I− 18. Compounds 7–18 were isolated and characterized by means of elemental analysis, IR and multinuclear NMR spectroscopy and by X‐ray diffraction of the compounds 7, 9, 10, 15, 16 and 18.
- Published
- 2020
42. N-Heterocyclic Silylenes as Metal–Metal Bridges and Metal–Halide Activators in Transition Metal Complexes
- Author
-
Mirjam J. Krahfuss and Udo Radius
- Subjects
chemistry.chemical_classification ,Silylation ,010405 organic chemistry ,Chemistry ,Ligand ,Iodide ,Silylene ,Halide ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,0104 chemical sciences ,Inorganic Chemistry ,Metal ,chemistry.chemical_compound ,Transition metal ,visual_art ,visual_art.visual_art_medium ,Metal metal ,Physical and Theoretical Chemistry - Abstract
Several examples are provided that NHSi (N-heterocyclic silylene) ligands are much better metal-metal bridging ligands as compared to NHCs and that NHSi also tends to insert much more easily into metal-halide bonds of transition metal complexes. Dipp2NHSi (1,3-bis(2,6-diisopropyphenyl)-1,3-diaza-4-silacyclopent-4-en-2-yliden) reacts with [{(η5-C5H5)Fe(CO)2}2] and [(η5-C5H5)2Ni] to yield, in contrast to the results obtained for analogous transformations with NHCs, the dinuclear silylene-bridged complexes [{(η5-C5H5)Fe(CO)}2(μ-CO)(μ-Dipp2NHSi)] (1) and [{(η5-C5H5)Ni(μ-Dipp2NHSi)}2] (2). The reaction with [(η5-C5H5)Ni(PPh3)(Cl)] leads with insertion of the silylene into the nickel-chloride bond to [(η5-C5H5)Ni(PPh3)(Dipp2NHSi-Cl)] (3). [Mn(CO)5(Cl)] reacts with 2 equiv of Dipp2NHSi to afford [Mn(CO)4(Dipp2NHSi)(Dipp2NHSi-Cl)] (5), in which one of the silylenes has inserted into the Mn-Cl bond and acts as a chloro silyl ligand. The reaction of 2 equiv of Dipp2NHSi with the corresponding iodide complex [Mn(CO)5(I)] leads to formation of the bis-silylene complex [Mn(CO)3(Dipp2NHSi)2(I)] (4).
- Published
- 2020
43. Nickel Tetracarbonyl as Starting Material for the Synthesis of NHC‐stabilized Nickel(II) Allyl Complexes
- Author
-
Udo Radius, Johannes H. J. Berthel, and Mirjam J. Krahfuß
- Subjects
Inorganic Chemistry ,Nickel ,chemistry.chemical_compound ,Chemistry ,Polymer chemistry ,Nickel tetracarbonyl ,chemistry.chemical_element - Published
- 2020
44. Palladium-Catalyzed Homocoupling of Highly Fluorinated Arylboronates: Studies of the Influence of Strongly vs Weakly Coordinating Solvents on the Reductive Elimination Process
- Author
-
Alexandra Friedrich, Todd B. Marder, Udo Radius, Florian Kerner, Arumugam Jayaraman, and Yudha P. Budiman
- Subjects
Ligand ,chemistry.chemical_element ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Medicinal chemistry ,Catalysis ,Reductive elimination ,3. Good health ,0104 chemical sciences ,Colloid and Surface Chemistry ,chemistry ,Palladium - Abstract
C–C reductive elimination from [PdL2(C6F5)2] to form polyfluorinated biaryls has been a challenge for over 50 years. Thus, palladium-catalyzed homocoupling of arylboronates (ArF–Bpin) containing tw...
- Published
- 2020
45. Regio‐ and Stereoselective Synthesis of 1,1‐Diborylalkenes via Brønsted Base‐Catalyzed Mixed Diboration of Alkynyl Esters and Amides with BpinBdan
- Author
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Jan Maier, Alexandra Friedrich, Webster L. Santos, Todd B. Marder, Udo Radius, Xiaocui Liu, Wenbo Ming, Xiaoling Luo, and Chemistry
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Borylation ,Alkyne ,Protonation ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Catalysis ,Deprotonation ,Physical and Theoretical Chemistry ,chemistry.chemical_classification ,Boronate esters ,010405 organic chemistry ,Chemistry ,Communication ,Structure elucidation ,Organic Chemistry ,Alkyne 1,1‐Diboration ,Communications ,0104 chemical sciences ,Reagent ,Cross-coupling ,Selectivity ,Brønsted–Lowry acid–base theory ,Cross‐coupling ,Synthesis design ,ddc:547 - Abstract
The NaOtBu‐catalyzed mixed 1,1‐diboration of terminal alkynes using the unsymmetrical diboron reagent BpinBdan (pin = pinacolato; dan = 1,8‐diaminonaphthalene) proceeds in a regio‐ and stereoselective fashion affording moderate to high yields of 1,1‐diborylalkenes bearing orthogonal boron protecting groups. It is applicable to gram‐scale synthesis without loss of yield or selectivity. The mixed 1,1‐diborylalkene products can be utilized in Suzuki–Miyaura cross‐coupling reactions which take place selectivly at the C–B site. DFT calculations suggest the NaOtBu‐catalyzed mixed 1,1‐diboration of alkynes occurs through deprotonation of the terminal alkyne, stepwise addition of BpinBdan to the terminal carbon followed by protonation with tBuOH. Experimentally observed selective formation of (Z)‐diborylalkenes is supported by our theoretical studies., Transition‐metal‐free mixed 1,1‐diboration of terminal alkynes with BpinBdan catalyzed by NaOtBu has been developed. The reaction proceeds in a regio‐ and stereoselective fashion affording (Z)‐diborylalkenes bearing orthogonal boron protecting groups.John Wiley & Sons, Ltd.
- Published
- 2020
46. N ‐Heterocyclic Carbene and Cyclic (Alkyl)(amino)carbene Complexes of Titanium(IV) and Titanium(III)
- Author
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Katharina Lubitz, Mirjam J. Krahfuß, Udo Radius, Holger Braunschweig, Günther Horrer, and Ivo Krummenacher
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Inorganic Chemistry ,chemistry.chemical_classification ,chemistry.chemical_compound ,chemistry ,Polymer chemistry ,chemistry.chemical_element ,ddc:546 ,Carbene ,Alkyl ,Titanium - Abstract
The reaction of one and two equivalents of the N ‐heterocyclic carbene IMes [IMes = 1,3‐bis(2,4,6‐trimethyl‐phenyl)imidazolin‐2‐ylidene] or the cyclic (alkyl)(amino)carbene cAAC\(^{Me}\) [cAAC\(^{Me}\) = 1‐(2,6‐diisopropyl‐phenyl)‐3,3,5,5‐tetra‐methylpyrrolidin‐2‐ylidene] with [TiCl\(_{4}\)] in n ‐hexane results in the formation of mono‐ and bis‐carbene complexes [TiCl\(_{4}\)(IMes)] 1 , [TiCl\(_{4}\)(IMes)2] 2 , [TiCl\(_{4}\)(cAAC\(^{Me}\))] 3 , and [TiCl\(_{4}\)(cAAC\(^{Me}\))\(_{2}\)] 4 , respectively. For comparison, the titanium(IV) NHC complex [TiCl\(_{4}\)(Ii Pr\(^{Me}\))] 5 (Ii Pr\(^{Me}\) = 1,3‐diisopropyl‐4,5‐dimethyl‐imidazolin‐2‐ylidene) has been synthesized and structurally characterized. The reaction of [TiCl\(_{4}\)(IMes)] 1 with PMe\(_{3}\) affords the mixed substituted complex [TiCl\(_{4}\)(IMes)(PMe\(_{3}\))] 6 . The reactions of [TiCl\(_{3}\)(THF)\(_{3}\)] with two equivalents of the carbenes IMes and cAAC\(^{Me}\) in n ‐hexane lead to the clean formation of the titanium(III) complexes [TiCl\(_{3}\)(IMes)\(_{2}\)] 7 and [TiCl\(_{3}\)(cAAC\(^{Me}\))\(_{2}\)] 8 . Compounds 1 –8 have been completely characterized by elemental analysis, IR and multinuclear NMR spectroscopy and for 2 –5 , 7 and 8 by X‐ray diffraction. Magnetometry in solution, EPR and UV/Vis spectroscopy and DFT calculations performed on 7 and 8 are indicative of a predominantly metal‐centered d\(^{1}\)‐radical in both cases.
- Published
- 2020
47. Coligand role in the NHC nickel catalyzed C–F bond activation: investigations on the insertion of bis(NHC) nickel into the C–F bond of hexafluorobenzene
- Author
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Lukas Tendera, Maximilian W. Kuntze-Fechner, Martin Diefenbach, Ivo Krummenacher, Hendrik Verplancke, Max C. Holthausen, Holger Braunschweig, Todd B. Marder, and Udo Radius
- Subjects
Aryl ,Difluoride ,Hexafluorobenzene ,chemistry.chemical_element ,General Chemistry ,Medicinal chemistry ,Redox ,Catalysis ,Metal ,Chemistry ,chemistry.chemical_compound ,Nickel ,Electron transfer ,chemistry ,visual_art ,visual_art.visual_art_medium - Abstract
The reaction of [Ni(Mes2Im)2] (1) (Mes2Im = 1,3-dimesityl-imidazolin-2-ylidene) with polyfluorinated arenes as well as mechanistic investigations concerning the insertion of 1 and [Ni(iPr2Im)2] (1ipr) (iPr2Im = 1,3-diisopropyl-imidazolin-2-ylidene) into the C–F bond of C6F6 is reported. The reaction of 1 with different fluoroaromatics leads to formation of the nickel fluoroaryl fluoride complexes trans-[Ni(Mes2Im)2(F)(ArF)] (ArF = 4-CF3-C6F42, C6F53, 2,3,5,6-C6F4N 4, 2,3,5,6-C6F4H 5, 2,3,5-C6F3H26, 3,5-C6F2H37) in fair to good yields with the exception of the formation of the pentafluorophenyl complex 3 (less than 20%). Radical species and other diamagnetic side products were detected for the reaction of 1 with C6F6, in line with a radical pathway for the C–F bond activation step using 1. The difluoride complex trans-[Ni(Mes2Im)2(F)2] (9), the bis(aryl) complex trans-[Ni(Mes2Im)2(C6F5)2] (15), the structurally characterized nickel(i) complex trans-[NiI(Mes2Im)2(C6F5)] (11) and the metal radical trans-[NiI(Mes2Im)2(F)] (12) were identified. Complex 11, and related [NiI(Mes2Im)2(2,3,5,6-C6F4H)] (13) and [NiI(Mes2Im)2(2,3,5-C6F3H2)] (14), were synthesized independently by reaction of trans-[Ni(Mes2Im)2(F)(ArF)] with PhSiH3. Simple electron transfer from 1 to C6F6 was excluded, as the redox potentials of the reaction partners do not match and [Ni(Mes2Im)2]+, which was prepared independently, was not detected. DFT calculations were performed on the insertion of [Ni(iPr2Im)2] (1ipr) and [Ni(Mes2Im)2] (1) into the C–F bond of C6F6. For 1ipr, concerted and NHC-assisted pathways were identified as having the lowest kinetic barriers, whereas for 1, a radical mechanism with fluoride abstraction and an NHC-assisted pathway are both associated with almost the same kinetic barrier., A combined experimental and theoretical study on the mechanism of the C–F bond activation of C6F6 with [Ni(NHC)2] is provided.
- Published
- 2020
48. N-Heterocyclic carbene and cyclic (alkyl)(amino)carbene adducts of gallium hydrides, gallium chlorides and gallium hydrochlorides
- Author
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Udo Radius, Christian Luz, Andreas Hock, and Luis Werner
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Inorganic Chemistry ,chemistry.chemical_classification ,Steric effects ,chemistry.chemical_compound ,chemistry ,Gallane ,Substituent ,Molecule ,Medicinal chemistry ,Oxidative addition ,Carbene ,Alkyl ,Adduct - Abstract
The synthesis and characterization of N-heterocyclic carbene (NHC) and cyclic (alkyl)(amino)carbene (cAAC) gallane and chlorogallane adducts of the type (NHC)·GaH3 (NHC = Me2ImMe1, iPr2Im 2, iPr2ImMe3 and Dipp2ImH4; Me2ImMe = 1,3,4,5-tetra-methyl-imidazolin-2-ylidene; R2Im = 1,3-di-organyl-imidazolin-2-ylidene; Dipp = 2,6-diisopropylphenyl; Dipp2ImH = 1,3-bis(2,6-diisopropylphenyl)-imidazolidin-2-ylidene), (NHC)·GaH2Cl (NHC = iPr2ImMe9, Dipp2Im 10 and Dipp2ImH11; iPr2ImMe = 1,3 diisopropyl-4,5-dimethyl-imidazolin-2-ylidene), (NHC)·GaHCl2 (NHC = iPr2ImMe12, Dipp2Im 13 and Dipp2ImH14) and (cAACMe)·GaHCl215 is reported. Compounds 1-3 and 9-11 are unstable in solution as heating to the boiling temperature of toluene (110 °C) leads to decomposition into elemental gallium and the corresponding dihydroaminal NHC-H2. The reaction of the mono-NHC adducts with a second equivalent of NHC also afforded decomposition and formation of NHC-H2, whereas the reaction of the NHC-stabilized gallanes with one equivalent cAACMe leads to an insertion of the cAACMe carbene carbon atom into the Ga-H bond. The synthesis and characterization of (NHC)·GaH2(cAACMeH) (NHC = Me2ImMe5, iPr2ImMe6 and Dipp2Im 7), the products of an oxidative addition of (NHC)·GaH3 to cAACMe, are presented. The adduct (Dipp2ImH)·GaH34 reacts with two equivalents of cAACMe under the release of Dipp2ImH and insertion of two cAACMe molecules into the Ga-H bond to give the bisalkylgallane (cAACMeH)2GaH 8. If one or two hydrogen atoms of the NHC gallane adducts are replaced with an electron-withdrawing chloride substituent, a selective insertion of cAACMe into the Ga-H bond occurs only for the adducts of sterically less demanding NHCs such as iPr2ImMe. The reaction of cAACMe with (iPr2ImMe)·GaH2Cl 9 and (iPr2ImMe)·GaHCl212 afforded (iPr2ImMe)·GaHCl(cAACMeH) 16 and (iPr2ImMe)·GaCl2(cAACMeH) 17. The reaction of cAACMe with (NHC)·GaHCl2 and (NHC)·GaH2Cl (NHC = Dipp2Im, Dipp2ImH), adducts of the sterically more demanding NHCs, leads to an extrusion of the NHC to (cAACMe)·GaHCl215 and (cAACMeH)2GaCl 18.
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- 2020
49. Cu-mediated
- Author
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Mingming, Huang, Man, Tang, Jiefeng, Hu, Stephen A, Westcott, Udo, Radius, and Todd B, Marder
- Abstract
A Cu-catalysed borylation of aryl alkyl sulfones was developed for the high yield synthesis of versatile arylboronic esters using a readily prepared NHC-Cu catalyst. In addition, the selective cleavage of either alkyl(C)-sulfonyl or aryl(C)-sulfonyl bonds of a cyclic sulfone
- Published
- 2021
50. Base-Mediated Radical Borylation of Alkyl Sulfones
- Author
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Jiefeng Hu, Ivo Krummenacher, Mingming Huang, Alexandra Friedrich, Stephen A. Westcott, Holger Braunschweig, Todd B. Marder, and Udo Radius
- Subjects
chemistry.chemical_classification ,Primary (chemistry) ,Base (chemistry) ,Organic Chemistry ,Esters ,General Chemistry ,Transesterification ,Borylation ,Combinatorial chemistry ,Catalysis ,chemistry.chemical_compound ,chemistry ,Radical clock ,Functional group ,Sulfones ,ddc:546 ,Boronic acid ,Alkyl - Abstract
A practical and direct method was developed for the production of versatile alkyl boronate esters via transition metal-free borylation of primary and secondary alkyl sulfones. The key to the success of the strategy is the use of bis(neopentyl glycolato) diboron (B\(_{2}\)neop\(_{2}\)), with a stoichiometric amount of base as a promoter. The practicality and industrial potential of this protocol are highlighted by its wide functional group tolerance, the late-stage modification of complex compounds, no need for further transesterification, and operational simplicity. Radical clock, radical trap experiments, and EPR studies were conducted which show that the borylation process involves radical intermediates.
- Published
- 2021
Catalog
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