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Type: Journal article
Title: Copper mediated decyano decarboxylative coupling of cyanoacetate ligands: Pesci versus Lewis acid mechanism
Author: Li, J.
Khairallah, G.
Steinmetz, V.
Maitre, P.
O'Hair, R.
Citation: Dalton Transactions, 2015; 44(19):9230-9240
Publisher: Royal Society of Chemistry
Issue Date: 2015
ISSN: 1477-9226
Statement of
Jiawei Li, George N. Khairallah, Vincent Steinmetz, Philippe Maitre and Richard A. J. O'Hair
Abstract: A combination of gas-phase ion trap multistage mass spectrometry (MSn) experiments and density functional theory (DFT) calculations have been used to examine the mechanisms of the sequential decomposition reactions of copper cyanoacetate anions, [(NCCH2CO2)2Cu]−, introduced into the gas-phase via electrospray ionization. Gas phase IR spectroscopy, used to probe the coordination mode of the cyanoacetate ligands, revealed that the initial precursor ions are bound to the Cu via the carboxylate, [NCCH2CO2CuO2CCH2CN], 1. Multistage collision-induced dissociation (CID) of 1 gave sequential losses of CO2 and ethene. DFT calculations suggest that the lowest energy pathways for sequential decarboxylation involve Lewis acid mechanisms in which the binding of the cyanoacetate ligand sequentially rearranges from O to N: [NCCH2CO2CuO2CCH2CN]− → [NCCH2CO2CuNCCH2CO2]− → [NCCH2CO2CuNCCH2]− + CO2 and [NCCH2CO2CuNCCH2]− → [O2CCH2CNCuNCCH2]− → [CH2CNCuNCCH2]− + CO2. Loss of ethene involves sequential rearrangement of the binding of the cyanomethyl carbanion ligands from N to C: [CH2CNCuNCCH2]− → [NCCH2CuNCCH2]− → [NCCH2CuCH2CN]−. CH2[double bond, length as m-dash]CH2 loss then proceeds via a 1,2-dyotropic rearrangement to form [NCCuCH2CH2CN]− followed by β-cyanide transfer. This study highlights the rich mechanistic possibilities for metal mediated decarboxylation reactions involving ambidentate carboxylate ligands.
Description: First published online 24 Apr 2015
Rights: This journal is © The Royal Society of Chemistry 2015. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
RMID: 0030051265
DOI: 10.1039/c5dt00942a
Appears in Collections:Chemistry publications

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