Intermolecular N-H oxidative addition of ammonia, alkylamines, and arylamines to a planar σ 3 -phosphorus compound via an entropy-controlled electrophilic mechanism

Sean M. McCarthy, Yi Chun Lin, Deepa Devarajan, Ji Woong Chang, Hemant P. Yennawar, Robert Martin Rioux, Jr., Daniel H. Ess, Alexander T. Radosevich

Research output: Contribution to journalArticle

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Abstract

Ammonia, alkyl amines, and aryl amines are found to undergo rapid intermolecular N-H oxidative addition to a planar mononuclear Ï 3 -phosphorus compound (1). The pentacoordinate phosphorane products (1·[H][NHR]) are structurally robust, permitting full characterization by multinuclear NMR spectroscopy and single-crystal X-ray diffraction. Isothermal titration calorimetry was employed to quantify the enthalpy of the N-H oxidative addition of n-propylamine to 1 ( n PrNH 2 + 1 ↠1·[H][NH n Pr], Î"H rxn 298 = -10.6 kcal/mol). The kinetics of n-propylamine N-H oxidative addition were monitored by in situ UV absorption spectroscopy and determination of the rate law showed an unusually large molecularity (Î= k[1][ n PrNH 2 ] 3 ). Kinetic experiments conducted over the temperature range of 10-70 °C revealed that the reaction rate decreased with increasing temperature. Activation parameters extracted from an Eyring analysis (Î"H ⧧ = -0.8 ± 0.4 kcal/mol, Î"S ⧧ = -72 ± 2 cal/(mol·K)) indicate that the cleavage of strong N-H bonds by 1 is entropy controlled due to a highly ordered, high molecularity transition state. Density functional calculations indicate that a concerted oxidative addition via a classical three-center transition structure is energetically inaccessible. Rather, a stepwise heterolytic pathway is preferred, proceeding by initial amine-assisted N-H heterolysis upon complexation to the electrophilic phosphorus center followed by rate-controlling N ↠P proton transfer.

Original languageEnglish (US)
Pages (from-to)4640-4650
Number of pages11
JournalJournal of the American Chemical Society
Volume136
Issue number12
DOIs
StatePublished - Mar 26 2014

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Phosphorus Compounds
Phosphorus compounds
Entropy
Propylamines
Ammonia
Amines
Phosphoranes
Biomolecular Nuclear Magnetic Resonance
Calorimetry
Kinetics
Temperature
Proton transfer
Ultraviolet spectroscopy
Complexation
Titration
Absorption spectroscopy
X-Ray Diffraction
Phosphorus
Nuclear magnetic resonance spectroscopy
Reaction rates

All Science Journal Classification (ASJC) codes

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

Cite this

@article{ab4cf6ded81549cd85d172520ce47a94,
title = "Intermolecular N-H oxidative addition of ammonia, alkylamines, and arylamines to a planar σ 3 -phosphorus compound via an entropy-controlled electrophilic mechanism",
abstract = "Ammonia, alkyl amines, and aryl amines are found to undergo rapid intermolecular N-H oxidative addition to a planar mononuclear {\"I} 3 -phosphorus compound (1). The pentacoordinate phosphorane products (1·[H][NHR]) are structurally robust, permitting full characterization by multinuclear NMR spectroscopy and single-crystal X-ray diffraction. Isothermal titration calorimetry was employed to quantify the enthalpy of the N-H oxidative addition of n-propylamine to 1 ( n PrNH 2 + 1 {\^a}† 1·[H][NH n Pr], {\^I}{"}H rxn 298 = -10.6 kcal/mol). The kinetics of n-propylamine N-H oxidative addition were monitored by in situ UV absorption spectroscopy and determination of the rate law showed an unusually large molecularity ({\^I}= k[1][ n PrNH 2 ] 3 ). Kinetic experiments conducted over the temperature range of 10-70 °C revealed that the reaction rate decreased with increasing temperature. Activation parameters extracted from an Eyring analysis ({\^I}{"}H {\^a}§§ = -0.8 ± 0.4 kcal/mol, {\^I}{"}S {\^a}§§ = -72 ± 2 cal/(mol·K)) indicate that the cleavage of strong N-H bonds by 1 is entropy controlled due to a highly ordered, high molecularity transition state. Density functional calculations indicate that a concerted oxidative addition via a classical three-center transition structure is energetically inaccessible. Rather, a stepwise heterolytic pathway is preferred, proceeding by initial amine-assisted N-H heterolysis upon complexation to the electrophilic phosphorus center followed by rate-controlling N {\^a}† P proton transfer.",
author = "McCarthy, {Sean M.} and Lin, {Yi Chun} and Deepa Devarajan and Chang, {Ji Woong} and Yennawar, {Hemant P.} and {Rioux, Jr.}, {Robert Martin} and Ess, {Daniel H.} and Radosevich, {Alexander T.}",
year = "2014",
month = "3",
day = "26",
doi = "10.1021/ja412469e",
language = "English (US)",
volume = "136",
pages = "4640--4650",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
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Intermolecular N-H oxidative addition of ammonia, alkylamines, and arylamines to a planar σ 3 -phosphorus compound via an entropy-controlled electrophilic mechanism . / McCarthy, Sean M.; Lin, Yi Chun; Devarajan, Deepa; Chang, Ji Woong; Yennawar, Hemant P.; Rioux, Jr., Robert Martin; Ess, Daniel H.; Radosevich, Alexander T.

In: Journal of the American Chemical Society, Vol. 136, No. 12, 26.03.2014, p. 4640-4650.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Intermolecular N-H oxidative addition of ammonia, alkylamines, and arylamines to a planar σ 3 -phosphorus compound via an entropy-controlled electrophilic mechanism

AU - McCarthy, Sean M.

AU - Lin, Yi Chun

AU - Devarajan, Deepa

AU - Chang, Ji Woong

AU - Yennawar, Hemant P.

AU - Rioux, Jr., Robert Martin

AU - Ess, Daniel H.

AU - Radosevich, Alexander T.

PY - 2014/3/26

Y1 - 2014/3/26

N2 - Ammonia, alkyl amines, and aryl amines are found to undergo rapid intermolecular N-H oxidative addition to a planar mononuclear Ï 3 -phosphorus compound (1). The pentacoordinate phosphorane products (1·[H][NHR]) are structurally robust, permitting full characterization by multinuclear NMR spectroscopy and single-crystal X-ray diffraction. Isothermal titration calorimetry was employed to quantify the enthalpy of the N-H oxidative addition of n-propylamine to 1 ( n PrNH 2 + 1 ↠1·[H][NH n Pr], Î"H rxn 298 = -10.6 kcal/mol). The kinetics of n-propylamine N-H oxidative addition were monitored by in situ UV absorption spectroscopy and determination of the rate law showed an unusually large molecularity (Î= k[1][ n PrNH 2 ] 3 ). Kinetic experiments conducted over the temperature range of 10-70 °C revealed that the reaction rate decreased with increasing temperature. Activation parameters extracted from an Eyring analysis (Î"H ⧧ = -0.8 ± 0.4 kcal/mol, Î"S ⧧ = -72 ± 2 cal/(mol·K)) indicate that the cleavage of strong N-H bonds by 1 is entropy controlled due to a highly ordered, high molecularity transition state. Density functional calculations indicate that a concerted oxidative addition via a classical three-center transition structure is energetically inaccessible. Rather, a stepwise heterolytic pathway is preferred, proceeding by initial amine-assisted N-H heterolysis upon complexation to the electrophilic phosphorus center followed by rate-controlling N ↠P proton transfer.

AB - Ammonia, alkyl amines, and aryl amines are found to undergo rapid intermolecular N-H oxidative addition to a planar mononuclear Ï 3 -phosphorus compound (1). The pentacoordinate phosphorane products (1·[H][NHR]) are structurally robust, permitting full characterization by multinuclear NMR spectroscopy and single-crystal X-ray diffraction. Isothermal titration calorimetry was employed to quantify the enthalpy of the N-H oxidative addition of n-propylamine to 1 ( n PrNH 2 + 1 ↠1·[H][NH n Pr], Î"H rxn 298 = -10.6 kcal/mol). The kinetics of n-propylamine N-H oxidative addition were monitored by in situ UV absorption spectroscopy and determination of the rate law showed an unusually large molecularity (Î= k[1][ n PrNH 2 ] 3 ). Kinetic experiments conducted over the temperature range of 10-70 °C revealed that the reaction rate decreased with increasing temperature. Activation parameters extracted from an Eyring analysis (Î"H ⧧ = -0.8 ± 0.4 kcal/mol, Î"S ⧧ = -72 ± 2 cal/(mol·K)) indicate that the cleavage of strong N-H bonds by 1 is entropy controlled due to a highly ordered, high molecularity transition state. Density functional calculations indicate that a concerted oxidative addition via a classical three-center transition structure is energetically inaccessible. Rather, a stepwise heterolytic pathway is preferred, proceeding by initial amine-assisted N-H heterolysis upon complexation to the electrophilic phosphorus center followed by rate-controlling N ↠P proton transfer.

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