Racemic NHC-Iridium Complexes with Electron-Poor Diene Ligands and Their Reactivity in the Intramolecular Hydroamination Reaction

Pengchao Gao, Daven Foster, Gellért Sipos, Brian W. Skelton, Alexandre N. Sobolev, Stephen A. Moggach, Reto Dorta

Research output: Contribution to journalArticle

Abstract

TFB (tetrafluorobenzobarrelene), TCB (tetrachlorobenzobarrelene), and BB (benzobarrelene) are introduced as alternative diene ligands to COD (1,5-cyclooctadiene) for NHC-iridium complexes of the general formula [(NHC)Ir(diene)Cl]. This new class of compounds was fully characterized, including by X-ray crystallography of appropriate single crystals. The steric requirements of three different NHC ligands as well as the diene ligands were analyzed using the SambVca program. The corresponding cationic and catalytically active [(NHC)Ir(diene)][PF6] complexes were generated via chloride abstraction with AgPF6. Where possible, these species were isolated and fully characterized. The less stable members were freshly made before being tested as catalysts in a prototypical intramolecular hydroamination reaction of an unactivated aminoalkene. A comparison shows how both diene as well as NHC ligands profoundly influence the catalytic activity and point toward future modifications to be made to these catalysts.

Original languageEnglish
Pages (from-to)3568-3581
JournalOrganometallics
Volume38
Issue number19
DOIs
Publication statusPublished - 5 Sep 2019

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Iridium
dienes
iridium
reactivity
Ligands
ligands
Electrons
electrons
Catalysts
X ray crystallography
catalysts
Chlorides
Catalyst activity
crystallography
Single crystals
catalytic activity
chlorides
requirements
single crystals
x rays

Cite this

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title = "Racemic NHC-Iridium Complexes with Electron-Poor Diene Ligands and Their Reactivity in the Intramolecular Hydroamination Reaction",
abstract = "TFB (tetrafluorobenzobarrelene), TCB (tetrachlorobenzobarrelene), and BB (benzobarrelene) are introduced as alternative diene ligands to COD (1,5-cyclooctadiene) for NHC-iridium complexes of the general formula [(NHC)Ir(diene)Cl]. This new class of compounds was fully characterized, including by X-ray crystallography of appropriate single crystals. The steric requirements of three different NHC ligands as well as the diene ligands were analyzed using the SambVca program. The corresponding cationic and catalytically active [(NHC)Ir(diene)][PF6] complexes were generated via chloride abstraction with AgPF6. Where possible, these species were isolated and fully characterized. The less stable members were freshly made before being tested as catalysts in a prototypical intramolecular hydroamination reaction of an unactivated aminoalkene. A comparison shows how both diene as well as NHC ligands profoundly influence the catalytic activity and point toward future modifications to be made to these catalysts.",
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volume = "38",
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journal = "Organometallics",
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Racemic NHC-Iridium Complexes with Electron-Poor Diene Ligands and Their Reactivity in the Intramolecular Hydroamination Reaction. / Gao, Pengchao; Foster, Daven; Sipos, Gellért; Skelton, Brian W.; Sobolev, Alexandre N.; Moggach, Stephen A.; Dorta, Reto.

In: Organometallics, Vol. 38, No. 19, 05.09.2019, p. 3568-3581.

Research output: Contribution to journalArticle

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AU - Gao, Pengchao

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AU - Sipos, Gellért

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AU - Dorta, Reto

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AB - TFB (tetrafluorobenzobarrelene), TCB (tetrachlorobenzobarrelene), and BB (benzobarrelene) are introduced as alternative diene ligands to COD (1,5-cyclooctadiene) for NHC-iridium complexes of the general formula [(NHC)Ir(diene)Cl]. This new class of compounds was fully characterized, including by X-ray crystallography of appropriate single crystals. The steric requirements of three different NHC ligands as well as the diene ligands were analyzed using the SambVca program. The corresponding cationic and catalytically active [(NHC)Ir(diene)][PF6] complexes were generated via chloride abstraction with AgPF6. Where possible, these species were isolated and fully characterized. The less stable members were freshly made before being tested as catalysts in a prototypical intramolecular hydroamination reaction of an unactivated aminoalkene. A comparison shows how both diene as well as NHC ligands profoundly influence the catalytic activity and point toward future modifications to be made to these catalysts.

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