Computational and synthetic studies on the cyclometallation reaction of dimethylbenzylamine with [IrCl2Cp*]2

Role of the chelating base

Youcef Boutadla, David L. Davies, Stuart A. Macgregor, Amalia I. Poblador-Bahamonde

Research output: Contribution to journalArticle

Abstract

The results of a joint computational and experimental study of the cyclometallation reactions of dimethylbenzylamine (DMBA-H) with [IrCl 2Cp*]2 and a range of chelating bases are presented. With acetate, density functional theory calculations on the key intermediate, [Ir(DMBA-H)(?2-OAc)Cp]+, define a two-step C-H activation process involving initial ?2-?1 displacement of base to give an intermediate that is stabilized by internal H-bonding. Facile C-H bond cleavage then occurs via'ambiphilic metal ligand activation' (AMLA). A similar pattern is computed for other carboxylates and bicarbonate, and in each case the ease of C-H activation is governed by the accessibility of the ?2-?1 base displacement step; thus, more weakly coordinating bases promote C-H activation. For triflate, [Ir(DMBA-H)(?1-CF3SO3)Cp]+ is more stable than its ?2-isomer and C-H activation proceeds with a barrier of only 3.8 kcal mol-1. Experimental studies confirm that a range of carboxylates and triflate can effect cyclometallation; however, reactivity patterns are not consistent with the computed C-H activation barriers. Instead, the role of base in opening the [IrCl2Cp*] 2 dimer and subsequent formation of the [Ir(DMBA-H)(base)Cp*] + intermediates appears crucial. Calculations indicate these processes are far more favourable for acetate than for triflate. © The Royal Society of Chemistry 2009.

Original languageEnglish
Pages (from-to)5887-5893
Number of pages7
JournalDalton Transactions
Issue number30
DOIs
Publication statusPublished - 2009

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9,10-Dimethyl-1,2-benzanthracene
Acetates
Bicarbonates
Joints
Metals
Ligands

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@article{440a0be63b084f00a9e65fa8d61cb364,
title = "Computational and synthetic studies on the cyclometallation reaction of dimethylbenzylamine with [IrCl2Cp*]2: Role of the chelating base",
abstract = "The results of a joint computational and experimental study of the cyclometallation reactions of dimethylbenzylamine (DMBA-H) with [IrCl 2Cp*]2 and a range of chelating bases are presented. With acetate, density functional theory calculations on the key intermediate, [Ir(DMBA-H)(?2-OAc)Cp]+, define a two-step C-H activation process involving initial ?2-?1 displacement of base to give an intermediate that is stabilized by internal H-bonding. Facile C-H bond cleavage then occurs via'ambiphilic metal ligand activation' (AMLA). A similar pattern is computed for other carboxylates and bicarbonate, and in each case the ease of C-H activation is governed by the accessibility of the ?2-?1 base displacement step; thus, more weakly coordinating bases promote C-H activation. For triflate, [Ir(DMBA-H)(?1-CF3SO3)Cp]+ is more stable than its ?2-isomer and C-H activation proceeds with a barrier of only 3.8 kcal mol-1. Experimental studies confirm that a range of carboxylates and triflate can effect cyclometallation; however, reactivity patterns are not consistent with the computed C-H activation barriers. Instead, the role of base in opening the [IrCl2Cp*] 2 dimer and subsequent formation of the [Ir(DMBA-H)(base)Cp*] + intermediates appears crucial. Calculations indicate these processes are far more favourable for acetate than for triflate. {\circledC} The Royal Society of Chemistry 2009.",
author = "Youcef Boutadla and Davies, {David L.} and Macgregor, {Stuart A.} and Poblador-Bahamonde, {Amalia I.}",
year = "2009",
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Computational and synthetic studies on the cyclometallation reaction of dimethylbenzylamine with [IrCl2Cp*]2 : Role of the chelating base. / Boutadla, Youcef; Davies, David L.; Macgregor, Stuart A.; Poblador-Bahamonde, Amalia I.

In: Dalton Transactions, No. 30, 2009, p. 5887-5893.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Computational and synthetic studies on the cyclometallation reaction of dimethylbenzylamine with [IrCl2Cp*]2

T2 - Role of the chelating base

AU - Boutadla, Youcef

AU - Davies, David L.

AU - Macgregor, Stuart A.

AU - Poblador-Bahamonde, Amalia I.

PY - 2009

Y1 - 2009

N2 - The results of a joint computational and experimental study of the cyclometallation reactions of dimethylbenzylamine (DMBA-H) with [IrCl 2Cp*]2 and a range of chelating bases are presented. With acetate, density functional theory calculations on the key intermediate, [Ir(DMBA-H)(?2-OAc)Cp]+, define a two-step C-H activation process involving initial ?2-?1 displacement of base to give an intermediate that is stabilized by internal H-bonding. Facile C-H bond cleavage then occurs via'ambiphilic metal ligand activation' (AMLA). A similar pattern is computed for other carboxylates and bicarbonate, and in each case the ease of C-H activation is governed by the accessibility of the ?2-?1 base displacement step; thus, more weakly coordinating bases promote C-H activation. For triflate, [Ir(DMBA-H)(?1-CF3SO3)Cp]+ is more stable than its ?2-isomer and C-H activation proceeds with a barrier of only 3.8 kcal mol-1. Experimental studies confirm that a range of carboxylates and triflate can effect cyclometallation; however, reactivity patterns are not consistent with the computed C-H activation barriers. Instead, the role of base in opening the [IrCl2Cp*] 2 dimer and subsequent formation of the [Ir(DMBA-H)(base)Cp*] + intermediates appears crucial. Calculations indicate these processes are far more favourable for acetate than for triflate. © The Royal Society of Chemistry 2009.

AB - The results of a joint computational and experimental study of the cyclometallation reactions of dimethylbenzylamine (DMBA-H) with [IrCl 2Cp*]2 and a range of chelating bases are presented. With acetate, density functional theory calculations on the key intermediate, [Ir(DMBA-H)(?2-OAc)Cp]+, define a two-step C-H activation process involving initial ?2-?1 displacement of base to give an intermediate that is stabilized by internal H-bonding. Facile C-H bond cleavage then occurs via'ambiphilic metal ligand activation' (AMLA). A similar pattern is computed for other carboxylates and bicarbonate, and in each case the ease of C-H activation is governed by the accessibility of the ?2-?1 base displacement step; thus, more weakly coordinating bases promote C-H activation. For triflate, [Ir(DMBA-H)(?1-CF3SO3)Cp]+ is more stable than its ?2-isomer and C-H activation proceeds with a barrier of only 3.8 kcal mol-1. Experimental studies confirm that a range of carboxylates and triflate can effect cyclometallation; however, reactivity patterns are not consistent with the computed C-H activation barriers. Instead, the role of base in opening the [IrCl2Cp*] 2 dimer and subsequent formation of the [Ir(DMBA-H)(base)Cp*] + intermediates appears crucial. Calculations indicate these processes are far more favourable for acetate than for triflate. © The Royal Society of Chemistry 2009.

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DO - 10.1039/b905469c

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EP - 5893

JO - Dalton Transactions

JF - Dalton Transactions

SN - 1477-9226

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