Activation of nitriles by metal ligand cooperation. reversible formation of ketimido- and enamido-rhenium PNP pincer complexes and relevance to catalytic design

Matthias Vogt, Alexander Nerush, Mark A. Iron, Gregory Leitus, Yael Diskin-Posner, Linda J W Shimon, Yehoshoa Ben-David, David Milstein

Research output: Contribution to journalArticle

59 Citations (Scopus)

Abstract

The dearomatized complex cis-[Re(PNPtBu*)(CO)2] (4) undergoes cooperative activation of Cî - N triple bonds of nitriles via [1,3]-addition. Reversible C-C and Re-N bond formation in 4 was investigated in a combined experimental and computational study. The reversible formation of the ketimido complexes (5-7) was observed. When nitriles bearing an alpha methylene group are used, reversible formation of the enamido complexes (8 and 9) takes place. The reversibility of the activation of the nitriles in the resulting ketimido compounds was demonstrated by the displacement of p-CF 3-benzonitrile from cis-[Re(PNPtBu-N=CPh pCF3)(CO)2] (6) upon addition of an excess of benzonitrile and by the temperature-dependent [1,3]-addition of pivalonitrile to complex 4. The reversible binding of the nitrile in the enamido compound cis-[Re(PNP tBu-HNC=CHPh)(CO)2] (9) was demonstrated via the displacement of benzyl cyanide from 9 by CO. Computational studies suggest a stepwise activation of the nitriles by 4, with remarkably low activation barriers, involving precoordination of the nitrile group to the Re(I) center. The enamido complex 9 reacts via β-carbon methylation to give the primary imino complex cis-[Re(PNPtBu-HN=CC(Me)Ph)(CO)2]OTf 11. Upon deprotonation of 11 and subsequent addition of benzyl cyanide, complex 9 is regenerated and the monomethylation product 2-phenylpropanenitrile is released. Complexes 4 and 9 were found to catalyze the Michael addition of benzyl cyanide derivatives to α,β-unsaturated esters and carbonyls.

Original languageEnglish
Pages (from-to)17004-17018
Number of pages15
JournalJournal of the American Chemical Society
Volume135
Issue number45
DOIs
Publication statusPublished - Nov 13 2013

Fingerprint

Rhenium
Nitriles
Carbon Monoxide
Cyanides
Metals
Chemical activation
Ligands
Bearings (structural)
Deprotonation
Methylation
Esters
Derivatives
Carbon
Temperature
benzyl cyanide

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Activation of nitriles by metal ligand cooperation. reversible formation of ketimido- and enamido-rhenium PNP pincer complexes and relevance to catalytic design. / Vogt, Matthias; Nerush, Alexander; Iron, Mark A.; Leitus, Gregory; Diskin-Posner, Yael; Shimon, Linda J W; Ben-David, Yehoshoa; Milstein, David.

In: Journal of the American Chemical Society, Vol. 135, No. 45, 13.11.2013, p. 17004-17018.

Research output: Contribution to journalArticle

Vogt, Matthias ; Nerush, Alexander ; Iron, Mark A. ; Leitus, Gregory ; Diskin-Posner, Yael ; Shimon, Linda J W ; Ben-David, Yehoshoa ; Milstein, David. / Activation of nitriles by metal ligand cooperation. reversible formation of ketimido- and enamido-rhenium PNP pincer complexes and relevance to catalytic design. In: Journal of the American Chemical Society. 2013 ; Vol. 135, No. 45. pp. 17004-17018.
@article{7e78211fb07f4021ac02f2effc835bee,
title = "Activation of nitriles by metal ligand cooperation. reversible formation of ketimido- and enamido-rhenium PNP pincer complexes and relevance to catalytic design",
abstract = "The dearomatized complex cis-[Re(PNPtBu*)(CO)2] (4) undergoes cooperative activation of C{\^i} - N triple bonds of nitriles via [1,3]-addition. Reversible C-C and Re-N bond formation in 4 was investigated in a combined experimental and computational study. The reversible formation of the ketimido complexes (5-7) was observed. When nitriles bearing an alpha methylene group are used, reversible formation of the enamido complexes (8 and 9) takes place. The reversibility of the activation of the nitriles in the resulting ketimido compounds was demonstrated by the displacement of p-CF 3-benzonitrile from cis-[Re(PNPtBu-N=CPh pCF3)(CO)2] (6) upon addition of an excess of benzonitrile and by the temperature-dependent [1,3]-addition of pivalonitrile to complex 4. The reversible binding of the nitrile in the enamido compound cis-[Re(PNP tBu-HNC=CHPh)(CO)2] (9) was demonstrated via the displacement of benzyl cyanide from 9 by CO. Computational studies suggest a stepwise activation of the nitriles by 4, with remarkably low activation barriers, involving precoordination of the nitrile group to the Re(I) center. The enamido complex 9 reacts via β-carbon methylation to give the primary imino complex cis-[Re(PNPtBu-HN=CC(Me)Ph)(CO)2]OTf 11. Upon deprotonation of 11 and subsequent addition of benzyl cyanide, complex 9 is regenerated and the monomethylation product 2-phenylpropanenitrile is released. Complexes 4 and 9 were found to catalyze the Michael addition of benzyl cyanide derivatives to α,β-unsaturated esters and carbonyls.",
author = "Matthias Vogt and Alexander Nerush and Iron, {Mark A.} and Gregory Leitus and Yael Diskin-Posner and Shimon, {Linda J W} and Yehoshoa Ben-David and David Milstein",
year = "2013",
month = "11",
day = "13",
doi = "10.1021/ja4071859",
language = "English",
volume = "135",
pages = "17004--17018",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "45",

}

TY - JOUR

T1 - Activation of nitriles by metal ligand cooperation. reversible formation of ketimido- and enamido-rhenium PNP pincer complexes and relevance to catalytic design

AU - Vogt, Matthias

AU - Nerush, Alexander

AU - Iron, Mark A.

AU - Leitus, Gregory

AU - Diskin-Posner, Yael

AU - Shimon, Linda J W

AU - Ben-David, Yehoshoa

AU - Milstein, David

PY - 2013/11/13

Y1 - 2013/11/13

N2 - The dearomatized complex cis-[Re(PNPtBu*)(CO)2] (4) undergoes cooperative activation of Cî - N triple bonds of nitriles via [1,3]-addition. Reversible C-C and Re-N bond formation in 4 was investigated in a combined experimental and computational study. The reversible formation of the ketimido complexes (5-7) was observed. When nitriles bearing an alpha methylene group are used, reversible formation of the enamido complexes (8 and 9) takes place. The reversibility of the activation of the nitriles in the resulting ketimido compounds was demonstrated by the displacement of p-CF 3-benzonitrile from cis-[Re(PNPtBu-N=CPh pCF3)(CO)2] (6) upon addition of an excess of benzonitrile and by the temperature-dependent [1,3]-addition of pivalonitrile to complex 4. The reversible binding of the nitrile in the enamido compound cis-[Re(PNP tBu-HNC=CHPh)(CO)2] (9) was demonstrated via the displacement of benzyl cyanide from 9 by CO. Computational studies suggest a stepwise activation of the nitriles by 4, with remarkably low activation barriers, involving precoordination of the nitrile group to the Re(I) center. The enamido complex 9 reacts via β-carbon methylation to give the primary imino complex cis-[Re(PNPtBu-HN=CC(Me)Ph)(CO)2]OTf 11. Upon deprotonation of 11 and subsequent addition of benzyl cyanide, complex 9 is regenerated and the monomethylation product 2-phenylpropanenitrile is released. Complexes 4 and 9 were found to catalyze the Michael addition of benzyl cyanide derivatives to α,β-unsaturated esters and carbonyls.

AB - The dearomatized complex cis-[Re(PNPtBu*)(CO)2] (4) undergoes cooperative activation of Cî - N triple bonds of nitriles via [1,3]-addition. Reversible C-C and Re-N bond formation in 4 was investigated in a combined experimental and computational study. The reversible formation of the ketimido complexes (5-7) was observed. When nitriles bearing an alpha methylene group are used, reversible formation of the enamido complexes (8 and 9) takes place. The reversibility of the activation of the nitriles in the resulting ketimido compounds was demonstrated by the displacement of p-CF 3-benzonitrile from cis-[Re(PNPtBu-N=CPh pCF3)(CO)2] (6) upon addition of an excess of benzonitrile and by the temperature-dependent [1,3]-addition of pivalonitrile to complex 4. The reversible binding of the nitrile in the enamido compound cis-[Re(PNP tBu-HNC=CHPh)(CO)2] (9) was demonstrated via the displacement of benzyl cyanide from 9 by CO. Computational studies suggest a stepwise activation of the nitriles by 4, with remarkably low activation barriers, involving precoordination of the nitrile group to the Re(I) center. The enamido complex 9 reacts via β-carbon methylation to give the primary imino complex cis-[Re(PNPtBu-HN=CC(Me)Ph)(CO)2]OTf 11. Upon deprotonation of 11 and subsequent addition of benzyl cyanide, complex 9 is regenerated and the monomethylation product 2-phenylpropanenitrile is released. Complexes 4 and 9 were found to catalyze the Michael addition of benzyl cyanide derivatives to α,β-unsaturated esters and carbonyls.

UR - http://www.scopus.com/inward/record.url?scp=84887763610&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84887763610&partnerID=8YFLogxK

U2 - 10.1021/ja4071859

DO - 10.1021/ja4071859

M3 - Article

VL - 135

SP - 17004

EP - 17018

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 45

ER -