Backbone Reactivity of Lithium β-Diketiminate (NacNac) Complexes with CO 2, tBuNCO and iPrNCO

Research output: Contribution to journalArticle

Abstract

Though alkali metal NacNac (β-diketiminate) complexes have been utilised in synthesis as NacNac-transfer agents, studies of them in their own right with small molecules are exceptionally rare. Here, the lithium compound of the common 2,6-diisopropylphenyl-β-methyldiketiminate [NacNac(Dipp, Me)] ligand is investigated with carbon dioxide and isocyanates. In all four cases reaction occurs at the backbone γ-C atom of the NacNac ligand, which redistributes electronically into a diimine. Insertion of CO 2 gives an eight-atom carboxylate (Li 2O 4C 2) ring at the γ-C site in a dimer. Insertion of tBuNCO gives a secondary amide at the γ-C site in a monomer with TMEDA chelating lithium. Double insertion of tBuNCO and (adventitious) oxygen gives a dimer with a (LiO) 2 central core involving the latter source. Insertion of less bulky (iPrNCO) gives a dimer with dimerisation through the C=O bonds of the emergent secondary amide function.

LanguageEnglish
Number of pages8
JournalChemistry - A European Journal
Early online date1 Oct 2019
DOIs
Publication statusE-pub ahead of print - 1 Oct 2019

Fingerprint

Carbon Monoxide
Lithium
Dimers
Amides
Lithium Compounds
Lithium compounds
Ligands
Alkali Metals
Isocyanates
Atoms
Dimerization
Alkali metals
Chelation
Carbon Dioxide
Carbon dioxide
Monomers
Oxygen
Molecules

Keywords

  • β-diketiminates
  • carbon dioxide fixation
  • isocyanates
  • lithium
  • x-ray diffraction

Cite this

@article{4f835d95e71145ca83320185399e6bd6,
title = "Backbone Reactivity of Lithium β-Diketiminate (NacNac) Complexes with CO 2, tBuNCO and iPrNCO",
abstract = "Though alkali metal NacNac (β-diketiminate) complexes have been utilised in synthesis as NacNac-transfer agents, studies of them in their own right with small molecules are exceptionally rare. Here, the lithium compound of the common 2,6-diisopropylphenyl-β-methyldiketiminate [NacNac(Dipp, Me)] ligand is investigated with carbon dioxide and isocyanates. In all four cases reaction occurs at the backbone γ-C atom of the NacNac ligand, which redistributes electronically into a diimine. Insertion of CO 2 gives an eight-atom carboxylate (Li 2O 4C 2) ring at the γ-C site in a dimer. Insertion of tBuNCO gives a secondary amide at the γ-C site in a monomer with TMEDA chelating lithium. Double insertion of tBuNCO and (adventitious) oxygen gives a dimer with a (LiO) 2 central core involving the latter source. Insertion of less bulky (iPrNCO) gives a dimer with dimerisation through the C=O bonds of the emergent secondary amide function.",
keywords = "β-diketiminates, carbon dioxide fixation, isocyanates, lithium, x-ray diffraction",
author = "Gauld, {Richard M} and Ross McLellan and Kennedy, {Alan R.} and Jim Barker and Jacqueline Reid and Mulvey, {Robert M.}",
note = "This is the peer reviewed version of the following article: Gauld, RM, McLellan, R, Kennedy, AR, Barker, J, Reid, J & Mulvey, RM 2019, 'Backbone reactivity of the lithium β-diketiminate (NacNac) complexes with CO2, t-BuNCO and iPr-NCO' Chemistry - A European Journal, which has been published in final form at https://doi.org/10.1002/chem.201904013. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.",
year = "2019",
month = "10",
day = "1",
doi = "10.1002/chem.201904013",
language = "English",
journal = "Chemistry - A European Journal",
issn = "0947-6539",

}

TY - JOUR

T1 - Backbone Reactivity of Lithium β-Diketiminate (NacNac) Complexes with CO 2, tBuNCO and iPrNCO

AU - Gauld, Richard M

AU - McLellan, Ross

AU - Kennedy, Alan R.

AU - Barker, Jim

AU - Reid, Jacqueline

AU - Mulvey, Robert M.

N1 - This is the peer reviewed version of the following article: Gauld, RM, McLellan, R, Kennedy, AR, Barker, J, Reid, J & Mulvey, RM 2019, 'Backbone reactivity of the lithium β-diketiminate (NacNac) complexes with CO2, t-BuNCO and iPr-NCO' Chemistry - A European Journal, which has been published in final form at https://doi.org/10.1002/chem.201904013. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

PY - 2019/10/1

Y1 - 2019/10/1

N2 - Though alkali metal NacNac (β-diketiminate) complexes have been utilised in synthesis as NacNac-transfer agents, studies of them in their own right with small molecules are exceptionally rare. Here, the lithium compound of the common 2,6-diisopropylphenyl-β-methyldiketiminate [NacNac(Dipp, Me)] ligand is investigated with carbon dioxide and isocyanates. In all four cases reaction occurs at the backbone γ-C atom of the NacNac ligand, which redistributes electronically into a diimine. Insertion of CO 2 gives an eight-atom carboxylate (Li 2O 4C 2) ring at the γ-C site in a dimer. Insertion of tBuNCO gives a secondary amide at the γ-C site in a monomer with TMEDA chelating lithium. Double insertion of tBuNCO and (adventitious) oxygen gives a dimer with a (LiO) 2 central core involving the latter source. Insertion of less bulky (iPrNCO) gives a dimer with dimerisation through the C=O bonds of the emergent secondary amide function.

AB - Though alkali metal NacNac (β-diketiminate) complexes have been utilised in synthesis as NacNac-transfer agents, studies of them in their own right with small molecules are exceptionally rare. Here, the lithium compound of the common 2,6-diisopropylphenyl-β-methyldiketiminate [NacNac(Dipp, Me)] ligand is investigated with carbon dioxide and isocyanates. In all four cases reaction occurs at the backbone γ-C atom of the NacNac ligand, which redistributes electronically into a diimine. Insertion of CO 2 gives an eight-atom carboxylate (Li 2O 4C 2) ring at the γ-C site in a dimer. Insertion of tBuNCO gives a secondary amide at the γ-C site in a monomer with TMEDA chelating lithium. Double insertion of tBuNCO and (adventitious) oxygen gives a dimer with a (LiO) 2 central core involving the latter source. Insertion of less bulky (iPrNCO) gives a dimer with dimerisation through the C=O bonds of the emergent secondary amide function.

KW - β-diketiminates

KW - carbon dioxide fixation

KW - isocyanates

KW - lithium

KW - x-ray diffraction

U2 - 10.1002/chem.201904013

DO - 10.1002/chem.201904013

M3 - Article

JO - Chemistry - A European Journal

T2 - Chemistry - A European Journal

JF - Chemistry - A European Journal

SN - 0947-6539

ER -