Homo‐ and Heterodinuclear Ir and Rh Imine‐functionalized Protic NHC Complexes: Synthetic, Structural Studies, and Tautomerization/Metallotropism Insights

He, Fan; Wesolek, Marcel; Danopoulos, Andreas A.; Braunstein, Pierre

doi:10.1002/chem.201504030

Cited by 12 publications

(4 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Danopoulos and Braunstein described the reaction of imine-tethered imidazoles with the iridium(I) complex [IrCl(cod)] 2 (Scheme 11). 78,79 After initial formation of the N-imidazole complex 26, chloride abstraction with a thallium salt leads to formal tautomerization of the imidazole to afford the C,N-chelate pNHC iridium(I) complex 27. Synthesis of the rhodium analogue of 27 requires heating at 110 °C.…”

Section: Formal Tautomerization Of Azolesmentioning

confidence: 96%

“… , After initial formation of the N-imidazole complex 26 , chloride abstraction with a thallium salt leads to formal tautomerization of the imidazole to afford the C,N-chelate pNHC iridium(I) complex 27 . Synthesis of the rhodium analogue of 27 requires heating at 110 °C . The reaction of 26 with an additional amount of the iridium complex yields the dinuclear iridium(III) complex 28a , suggesting an oxidative addition pathway for the azole-to-pNHC tautomerization (see section ).…”

Section: Synthesismentioning

confidence: 99%

“…In their effort to obtain imine-tethered pNHC complexes (Scheme ), Danopoulos and Braunstein isolated the dinuclear hydrido-imidazolyl Ir III /Ir I complex 28a and found that 28a is easily converted (by reductive elimination) to the pNHC iridium(I) complex 27 upon chloride abstraction with a thallium salt. , This observation suggests that the formal tautomerization of 26 to 27 involves the Lewis acid-aided formation of complexes like 28a and 28b by an oxidative addition reaction, in accordance with the redox tautomerization mechanism.…”

Section: Synthesismentioning

confidence: 99%

“…Synthesis of the rhodium analogue of 27 requires heating at 110 °C. 79 The reaction of 26 with an additional amount of the iridium complex yields the dinuclear iridium(III) complex 28a, suggesting an oxidative addition pathway for the azole-to-pNHC tautomerization (see section 2.1.3).…”

Section: Formal Tautomerization Of Azolesmentioning

confidence: 99%

See 3 more Smart Citations

Complexes Bearing Protic N-Heterocyclic Carbene Ligands

2018

View full text Add to dashboard Cite

Complexes bearing protic N-heterocyclic carbenes (protic NHCs, pNHCs), defined as cyclic carbenes stabilized by two heteroatoms including at least one NH group, have been less explored in comparison to the conventional N,N'-disubstituted NHCs. The small and reactive NH group of the pNHCs differentiates this class of compounds from the classical NR,NR-NHCs with regard to their properties and reactivity. While the free pNHCs have so far eluded isolation due to isomerization to the azole tautomer, a significant number of transition-metal pNHC complexes have by now been prepared by a variety of methods. This article reviews the coordination chemistry of the pNHCs. Synthetic approaches toward complexes of pNHCs are first described, followed by a discussion of the properties and reactivity of pNHC complexes with emphasis on the Brønsted-acidic nature of the NH wingtip. Involvement of the pNHC ligands in catalytically active intermediates and in cooperative catalysis is also discussed.

show abstract

Section: Formal Tautomerization Of Azolesmentioning

confidence: 96%

Section: Synthesismentioning

confidence: 99%

Section: Synthesismentioning

confidence: 99%

Section: Formal Tautomerization Of Azolesmentioning

confidence: 99%

See 2 more Smart Citations

Complexes Bearing Protic N-Heterocyclic Carbene Ligands

2018

View full text Add to dashboard Cite

show abstract

Monosubstituted, Anionic Imidazolyl Ligands from N−H NHC Precursors and Their Activity in Pd‐Catalyzed Cross‐Coupling Reactions

et al. 2020

View full text Add to dashboard Cite

show abstract

Protic N‐Heterocyclic Carbene Versus Pyrazole: Rigorous Comparison of Proton‐ and Electron‐Donating Abilities in a Pincer‐Type Framework

Toda

Yoshinari

Ikariya

et al. 2016

Chemistry A European J

View full text Add to dashboard Cite

Evaluation of the acidity of proton-responsive ligands such as protic N-heterocyclic carbenes (NHCs) bearing an NH-wingtip provides a key to understanding the metal-ligand cooperation in enzymatic and artificial catalysis. Here, we design a CNN pincer-type ruthenium complex 2 bearing protic NHC and isoelectronic pyrazole units in a symmetrical skeleton, to compare their acidities and electron-donating abilities. The synthesis is achieved by direct C-H metalation of 2-(imidazol-1-yl)-6-(pyrazol-3-yl)pyridine with [RuCl (PPh ) ]. N-Labeling experiments confirm that deprotonation of 2 occurs first at the pyrazole side, indicating clearly that the protic pyrazole is more acidic than the NHC group. The electrochemical measurements as well as derivatization to carbonyl complexes demonstrate that the protic NHC is more electron-donating than pyrazole in both protonated and deprotonated forms.

show abstract

Homo‐ and Heterodinuclear Ir and Rh Imine‐functionalized Protic NHC Complexes: Synthetic, Structural Studies, and Tautomerization/Metallotropism Insights

Cited by 12 publications

References 57 publications

Complexes Bearing Protic N-Heterocyclic Carbene Ligands

Complexes Bearing Protic N-Heterocyclic Carbene Ligands

Monosubstituted, Anionic Imidazolyl Ligands from N−H NHC Precursors and Their Activity in Pd‐Catalyzed Cross‐Coupling Reactions

Protic N‐Heterocyclic Carbene Versus Pyrazole: Rigorous Comparison of Proton‐ and Electron‐Donating Abilities in a Pincer‐Type Framework

Contact Info

Product

Resources

About