Synthetic, mechanistic, and computational investigations of nitrile-alkyne cross-metathesis

Andrea M. Geyer, Eric Wiedner, J. Brannon Gary, Robyn L. Gdula, Nicola C. Kuhlmann, Marc J A Johnson, Barry D. Dunietz, Jeff W. Kampf

Research output: Contribution to journalArticle

56 Citations (Scopus)

Abstract

The terminal nitride complexes NW(OC(CF3)2Me) 3(DME) (1-DME), [Li(DME)2][NW(OC(CF3) 2Me)4] (2), and [NW(OCMe2CF3) 3]3 (3) were prepared in good yield by salt elimination from [NWCl3]4. X-ray structures revealed that 1-DME and 2 are monomeric in the solid state. All three complexes catalyze the cross-metathesis of 3-hexyne with assorted nitriles to form propionitrile and the corresponding alkyne. Propylidyne and substituted benzylidyne complexes RCW(OC(CF3)2Me)3 were isolated in good yield upon reaction of 1-DME with 3-hexyne or 1-aryl-1-butyne. The corresponding reactions failed for 3. Instead, EtCW(OC(CF3)Me2) 3 (6) was prepared via the reaction of W2(OC(CF 3)Me2)6 with 3-hexyne at 95°C. Benzylidyne complexes of the form ArCW(OC(CF3)Me2)3 (Ar = aryl) then were prepared by treatment of 6 with the appropriate symmetrical alkyne ArCCAr. Three coupled cycles for the interconversion of 1-DME with the corresponding propylidyne and benzylidyne complexes via [2 + 2] cycloaddition-cycloreversion were examined for reversibility. Stoichiometric reactions revealed that both nitrile-alkyne cross-metathesis (NACM) cycles as well as the alkyne cross-metathesis (ACM) cycle operated reversibly in this system. With catalyst 3, depending on the aryl group used, at least one step in one of the NACM cycles was irreversible. In general, catalyst 1-DME afforded more rapid reaction than did 3 under comparable conditions. However, 3 displayed a slightly improved tolerance of polar functional groups than did 1-DME. For both 1-DME and 3, ACM is more rapid than NACM under typical conditions. Alkyne polymerization (AP) is a competing reaction with both 1-DME and 3. It can be suppressed but not entirely eliminated via manipulation of the catalyst concentration. As AP selectively removes 3-hexyne from the system, tandem NACM-ACM-AP can be used to prepare symmetrically substituted alkynes with good selectivity, including an arylene-ethynylene macrocycle. Alternatively, unsymmetrical alkynes of the form EtCCR (R variable) can be prepared with good selectivity via the reaction of RCN with excess 3-hexyne under conditions that suppress AP. DFT calculations support a [2 + 2] cycloaddition-cycloreversion mechanism analogous to that of alkyne metathesis. The barrier to azametalacyclobutadiene ring formation/breakup is greater than that for the corresponding metalacyclobutadiene. Two distinct high-energy azametalacyclobutadiene intermediates were found. These adopted a distorted square pyramidal geometry with significant bond localization.

Original languageEnglish
Pages (from-to)8984-8999
Number of pages16
JournalJournal of the American Chemical Society
Volume130
Issue number28
DOIs
Publication statusPublished - Jul 16 2008

Fingerprint

Nitriles
Alkynes
Polymerization
Cycloaddition
Catalysts
Discrete Fourier transforms
Nitrides
Functional groups
Salts
X rays
Geometry
Cycloaddition Reaction

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Geyer, A. M., Wiedner, E., Gary, J. B., Gdula, R. L., Kuhlmann, N. C., Johnson, M. J. A., ... Kampf, J. W. (2008). Synthetic, mechanistic, and computational investigations of nitrile-alkyne cross-metathesis. Journal of the American Chemical Society, 130(28), 8984-8999. https://doi.org/10.1021/ja800020w

Synthetic, mechanistic, and computational investigations of nitrile-alkyne cross-metathesis. / Geyer, Andrea M.; Wiedner, Eric; Gary, J. Brannon; Gdula, Robyn L.; Kuhlmann, Nicola C.; Johnson, Marc J A; Dunietz, Barry D.; Kampf, Jeff W.

In: Journal of the American Chemical Society, Vol. 130, No. 28, 16.07.2008, p. 8984-8999.

Research output: Contribution to journalArticle

Geyer, AM, Wiedner, E, Gary, JB, Gdula, RL, Kuhlmann, NC, Johnson, MJA, Dunietz, BD & Kampf, JW 2008, 'Synthetic, mechanistic, and computational investigations of nitrile-alkyne cross-metathesis', Journal of the American Chemical Society, vol. 130, no. 28, pp. 8984-8999. https://doi.org/10.1021/ja800020w
Geyer, Andrea M. ; Wiedner, Eric ; Gary, J. Brannon ; Gdula, Robyn L. ; Kuhlmann, Nicola C. ; Johnson, Marc J A ; Dunietz, Barry D. ; Kampf, Jeff W. / Synthetic, mechanistic, and computational investigations of nitrile-alkyne cross-metathesis. In: Journal of the American Chemical Society. 2008 ; Vol. 130, No. 28. pp. 8984-8999.
@article{6feb827932054117b5b381db0e6c8346,
title = "Synthetic, mechanistic, and computational investigations of nitrile-alkyne cross-metathesis",
abstract = "The terminal nitride complexes NW(OC(CF3)2Me) 3(DME) (1-DME), [Li(DME)2][NW(OC(CF3) 2Me)4] (2), and [NW(OCMe2CF3) 3]3 (3) were prepared in good yield by salt elimination from [NWCl3]4. X-ray structures revealed that 1-DME and 2 are monomeric in the solid state. All three complexes catalyze the cross-metathesis of 3-hexyne with assorted nitriles to form propionitrile and the corresponding alkyne. Propylidyne and substituted benzylidyne complexes RCW(OC(CF3)2Me)3 were isolated in good yield upon reaction of 1-DME with 3-hexyne or 1-aryl-1-butyne. The corresponding reactions failed for 3. Instead, EtCW(OC(CF3)Me2) 3 (6) was prepared via the reaction of W2(OC(CF 3)Me2)6 with 3-hexyne at 95°C. Benzylidyne complexes of the form ArCW(OC(CF3)Me2)3 (Ar = aryl) then were prepared by treatment of 6 with the appropriate symmetrical alkyne ArCCAr. Three coupled cycles for the interconversion of 1-DME with the corresponding propylidyne and benzylidyne complexes via [2 + 2] cycloaddition-cycloreversion were examined for reversibility. Stoichiometric reactions revealed that both nitrile-alkyne cross-metathesis (NACM) cycles as well as the alkyne cross-metathesis (ACM) cycle operated reversibly in this system. With catalyst 3, depending on the aryl group used, at least one step in one of the NACM cycles was irreversible. In general, catalyst 1-DME afforded more rapid reaction than did 3 under comparable conditions. However, 3 displayed a slightly improved tolerance of polar functional groups than did 1-DME. For both 1-DME and 3, ACM is more rapid than NACM under typical conditions. Alkyne polymerization (AP) is a competing reaction with both 1-DME and 3. It can be suppressed but not entirely eliminated via manipulation of the catalyst concentration. As AP selectively removes 3-hexyne from the system, tandem NACM-ACM-AP can be used to prepare symmetrically substituted alkynes with good selectivity, including an arylene-ethynylene macrocycle. Alternatively, unsymmetrical alkynes of the form EtCCR (R variable) can be prepared with good selectivity via the reaction of RCN with excess 3-hexyne under conditions that suppress AP. DFT calculations support a [2 + 2] cycloaddition-cycloreversion mechanism analogous to that of alkyne metathesis. The barrier to azametalacyclobutadiene ring formation/breakup is greater than that for the corresponding metalacyclobutadiene. Two distinct high-energy azametalacyclobutadiene intermediates were found. These adopted a distorted square pyramidal geometry with significant bond localization.",
author = "Geyer, {Andrea M.} and Eric Wiedner and Gary, {J. Brannon} and Gdula, {Robyn L.} and Kuhlmann, {Nicola C.} and Johnson, {Marc J A} and Dunietz, {Barry D.} and Kampf, {Jeff W.}",
year = "2008",
month = "7",
day = "16",
doi = "10.1021/ja800020w",
language = "English",
volume = "130",
pages = "8984--8999",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "28",

}

TY - JOUR

T1 - Synthetic, mechanistic, and computational investigations of nitrile-alkyne cross-metathesis

AU - Geyer, Andrea M.

AU - Wiedner, Eric

AU - Gary, J. Brannon

AU - Gdula, Robyn L.

AU - Kuhlmann, Nicola C.

AU - Johnson, Marc J A

AU - Dunietz, Barry D.

AU - Kampf, Jeff W.

PY - 2008/7/16

Y1 - 2008/7/16

N2 - The terminal nitride complexes NW(OC(CF3)2Me) 3(DME) (1-DME), [Li(DME)2][NW(OC(CF3) 2Me)4] (2), and [NW(OCMe2CF3) 3]3 (3) were prepared in good yield by salt elimination from [NWCl3]4. X-ray structures revealed that 1-DME and 2 are monomeric in the solid state. All three complexes catalyze the cross-metathesis of 3-hexyne with assorted nitriles to form propionitrile and the corresponding alkyne. Propylidyne and substituted benzylidyne complexes RCW(OC(CF3)2Me)3 were isolated in good yield upon reaction of 1-DME with 3-hexyne or 1-aryl-1-butyne. The corresponding reactions failed for 3. Instead, EtCW(OC(CF3)Me2) 3 (6) was prepared via the reaction of W2(OC(CF 3)Me2)6 with 3-hexyne at 95°C. Benzylidyne complexes of the form ArCW(OC(CF3)Me2)3 (Ar = aryl) then were prepared by treatment of 6 with the appropriate symmetrical alkyne ArCCAr. Three coupled cycles for the interconversion of 1-DME with the corresponding propylidyne and benzylidyne complexes via [2 + 2] cycloaddition-cycloreversion were examined for reversibility. Stoichiometric reactions revealed that both nitrile-alkyne cross-metathesis (NACM) cycles as well as the alkyne cross-metathesis (ACM) cycle operated reversibly in this system. With catalyst 3, depending on the aryl group used, at least one step in one of the NACM cycles was irreversible. In general, catalyst 1-DME afforded more rapid reaction than did 3 under comparable conditions. However, 3 displayed a slightly improved tolerance of polar functional groups than did 1-DME. For both 1-DME and 3, ACM is more rapid than NACM under typical conditions. Alkyne polymerization (AP) is a competing reaction with both 1-DME and 3. It can be suppressed but not entirely eliminated via manipulation of the catalyst concentration. As AP selectively removes 3-hexyne from the system, tandem NACM-ACM-AP can be used to prepare symmetrically substituted alkynes with good selectivity, including an arylene-ethynylene macrocycle. Alternatively, unsymmetrical alkynes of the form EtCCR (R variable) can be prepared with good selectivity via the reaction of RCN with excess 3-hexyne under conditions that suppress AP. DFT calculations support a [2 + 2] cycloaddition-cycloreversion mechanism analogous to that of alkyne metathesis. The barrier to azametalacyclobutadiene ring formation/breakup is greater than that for the corresponding metalacyclobutadiene. Two distinct high-energy azametalacyclobutadiene intermediates were found. These adopted a distorted square pyramidal geometry with significant bond localization.

AB - The terminal nitride complexes NW(OC(CF3)2Me) 3(DME) (1-DME), [Li(DME)2][NW(OC(CF3) 2Me)4] (2), and [NW(OCMe2CF3) 3]3 (3) were prepared in good yield by salt elimination from [NWCl3]4. X-ray structures revealed that 1-DME and 2 are monomeric in the solid state. All three complexes catalyze the cross-metathesis of 3-hexyne with assorted nitriles to form propionitrile and the corresponding alkyne. Propylidyne and substituted benzylidyne complexes RCW(OC(CF3)2Me)3 were isolated in good yield upon reaction of 1-DME with 3-hexyne or 1-aryl-1-butyne. The corresponding reactions failed for 3. Instead, EtCW(OC(CF3)Me2) 3 (6) was prepared via the reaction of W2(OC(CF 3)Me2)6 with 3-hexyne at 95°C. Benzylidyne complexes of the form ArCW(OC(CF3)Me2)3 (Ar = aryl) then were prepared by treatment of 6 with the appropriate symmetrical alkyne ArCCAr. Three coupled cycles for the interconversion of 1-DME with the corresponding propylidyne and benzylidyne complexes via [2 + 2] cycloaddition-cycloreversion were examined for reversibility. Stoichiometric reactions revealed that both nitrile-alkyne cross-metathesis (NACM) cycles as well as the alkyne cross-metathesis (ACM) cycle operated reversibly in this system. With catalyst 3, depending on the aryl group used, at least one step in one of the NACM cycles was irreversible. In general, catalyst 1-DME afforded more rapid reaction than did 3 under comparable conditions. However, 3 displayed a slightly improved tolerance of polar functional groups than did 1-DME. For both 1-DME and 3, ACM is more rapid than NACM under typical conditions. Alkyne polymerization (AP) is a competing reaction with both 1-DME and 3. It can be suppressed but not entirely eliminated via manipulation of the catalyst concentration. As AP selectively removes 3-hexyne from the system, tandem NACM-ACM-AP can be used to prepare symmetrically substituted alkynes with good selectivity, including an arylene-ethynylene macrocycle. Alternatively, unsymmetrical alkynes of the form EtCCR (R variable) can be prepared with good selectivity via the reaction of RCN with excess 3-hexyne under conditions that suppress AP. DFT calculations support a [2 + 2] cycloaddition-cycloreversion mechanism analogous to that of alkyne metathesis. The barrier to azametalacyclobutadiene ring formation/breakup is greater than that for the corresponding metalacyclobutadiene. Two distinct high-energy azametalacyclobutadiene intermediates were found. These adopted a distorted square pyramidal geometry with significant bond localization.

UR - http://www.scopus.com/inward/record.url?scp=47349096305&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=47349096305&partnerID=8YFLogxK

U2 - 10.1021/ja800020w

DO - 10.1021/ja800020w

M3 - Article

VL - 130

SP - 8984

EP - 8999

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 28

ER -