In-Depth Study on Chloride Abstractions from (NHC)Ir(COD)CI Complexes

Gellert Sipos, Pengchao Gao, Daven Foster, Brian W. Skelton, Alexandre N. Sobolev, Reto Dorta

Research output: Contribution to journalArticle

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Abstract

While attempting to prepare a series of cationic NHC-Ir complexes of general formula [(NHC)Ir(COD)](+) via the silver salt metathesis reaction of its precursor (NHC)Ir(COD)Cl in dichloromethane, we unexpectedly synthesized [(mu-Cl){(2,7-SICyNap)Ir(COD))center dot{Ag(OTf)}], a chlotide-bridged Ir-Ag adduct. This result led us to investigate the chloride abstraction from the (NHC)Ir(COD)Cl systein in detail. We show how the outcome of this ubiquitous reaction is dependent on a fine balance between the nucleophilicity of the weakly coordinating anion (WCA) and the polarity/coordinating ability of the reaction medium. A frequently encountered alternative to using silver salts is also presented and compared. The experimental difference in the reactivitieS of cationic catalysts in a representative intramolecular hydroamination reaction shows how a cationic Ir-Ag adduct can fail to deliver the reaction product through what appears to be a stabilization of the catalytically inactive iridium-silver intermediate by the educt.

Original languageEnglish
Pages (from-to)801-817
Number of pages17
JournalOrganometallics
Volume36
Issue number4
Early online date6 Feb 2017
DOIs
Publication statusPublished - 27 Feb 2017

Cite this

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title = "In-Depth Study on Chloride Abstractions from (NHC)Ir(COD)CI Complexes",
abstract = "While attempting to prepare a series of cationic NHC-Ir complexes of general formula [(NHC)Ir(COD)](+) via the silver salt metathesis reaction of its precursor (NHC)Ir(COD)Cl in dichloromethane, we unexpectedly synthesized [(mu-Cl){(2,7-SICyNap)Ir(COD))center dot{Ag(OTf)}], a chlotide-bridged Ir-Ag adduct. This result led us to investigate the chloride abstraction from the (NHC)Ir(COD)Cl systein in detail. We show how the outcome of this ubiquitous reaction is dependent on a fine balance between the nucleophilicity of the weakly coordinating anion (WCA) and the polarity/coordinating ability of the reaction medium. A frequently encountered alternative to using silver salts is also presented and compared. The experimental difference in the reactivitieS of cationic catalysts in a representative intramolecular hydroamination reaction shows how a cationic Ir-Ag adduct can fail to deliver the reaction product through what appears to be a stabilization of the catalytically inactive iridium-silver intermediate by the educt.",
keywords = "WEAKLY COORDINATING ANIONS, SILVER SALT METATHESIS, TRANSITION-METAL-COMPLEXES, C-H FUNCTIONALIZATION, RAY CRYSTAL-STRUCTURE, MOLECULAR-STRUCTURE, IRIDIUM COMPLEXES, ENANTIOSELECTIVE HYDROGENATION, STRUCTURAL-CHARACTERIZATION, ASYMMETRIC HYDROAMINATION",
author = "Gellert Sipos and Pengchao Gao and Daven Foster and Skelton, {Brian W.} and Sobolev, {Alexandre N.} and Reto Dorta",
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In-Depth Study on Chloride Abstractions from (NHC)Ir(COD)CI Complexes. / Sipos, Gellert; Gao, Pengchao; Foster, Daven; Skelton, Brian W.; Sobolev, Alexandre N.; Dorta, Reto.

In: Organometallics, Vol. 36, No. 4, 27.02.2017, p. 801-817.

Research output: Contribution to journalArticle

TY - JOUR

T1 - In-Depth Study on Chloride Abstractions from (NHC)Ir(COD)CI Complexes

AU - Sipos, Gellert

AU - Gao, Pengchao

AU - Foster, Daven

AU - Skelton, Brian W.

AU - Sobolev, Alexandre N.

AU - Dorta, Reto

PY - 2017/2/27

Y1 - 2017/2/27

N2 - While attempting to prepare a series of cationic NHC-Ir complexes of general formula [(NHC)Ir(COD)](+) via the silver salt metathesis reaction of its precursor (NHC)Ir(COD)Cl in dichloromethane, we unexpectedly synthesized [(mu-Cl){(2,7-SICyNap)Ir(COD))center dot{Ag(OTf)}], a chlotide-bridged Ir-Ag adduct. This result led us to investigate the chloride abstraction from the (NHC)Ir(COD)Cl systein in detail. We show how the outcome of this ubiquitous reaction is dependent on a fine balance between the nucleophilicity of the weakly coordinating anion (WCA) and the polarity/coordinating ability of the reaction medium. A frequently encountered alternative to using silver salts is also presented and compared. The experimental difference in the reactivitieS of cationic catalysts in a representative intramolecular hydroamination reaction shows how a cationic Ir-Ag adduct can fail to deliver the reaction product through what appears to be a stabilization of the catalytically inactive iridium-silver intermediate by the educt.

AB - While attempting to prepare a series of cationic NHC-Ir complexes of general formula [(NHC)Ir(COD)](+) via the silver salt metathesis reaction of its precursor (NHC)Ir(COD)Cl in dichloromethane, we unexpectedly synthesized [(mu-Cl){(2,7-SICyNap)Ir(COD))center dot{Ag(OTf)}], a chlotide-bridged Ir-Ag adduct. This result led us to investigate the chloride abstraction from the (NHC)Ir(COD)Cl systein in detail. We show how the outcome of this ubiquitous reaction is dependent on a fine balance between the nucleophilicity of the weakly coordinating anion (WCA) and the polarity/coordinating ability of the reaction medium. A frequently encountered alternative to using silver salts is also presented and compared. The experimental difference in the reactivitieS of cationic catalysts in a representative intramolecular hydroamination reaction shows how a cationic Ir-Ag adduct can fail to deliver the reaction product through what appears to be a stabilization of the catalytically inactive iridium-silver intermediate by the educt.

KW - WEAKLY COORDINATING ANIONS

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KW - TRANSITION-METAL-COMPLEXES

KW - C-H FUNCTIONALIZATION

KW - RAY CRYSTAL-STRUCTURE

KW - MOLECULAR-STRUCTURE

KW - IRIDIUM COMPLEXES

KW - ENANTIOSELECTIVE HYDROGENATION

KW - STRUCTURAL-CHARACTERIZATION

KW - ASYMMETRIC HYDROAMINATION

U2 - 10.1021/acs.organomet.6b00864

DO - 10.1021/acs.organomet.6b00864

M3 - Article

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SP - 801

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JO - Organometallics

JF - Organometallics

SN - 0276-7333

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