Synthetic and theoretical MO calculational studies of lithiotriazine intermediates produced during alkyllithium-induced cyclotrimerisation reactions of organic nitriles, and comparison of their structures with that of a methylmagnesiotriazine derivative

D.R. Armstrong, Kenneth. W. Henderson, M. MacGregor, Robert Mulvey, M.J Ross, W. Clegg, P.A. O'Neil

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Abstract

Benzonitrile can be readily cyclotrimerised by treatment with a suitable alkyllithium to give a simple triazine, or to a solvated lithiodihydrotriazine derivative. Which cyclic product dominates depends mainly on the source of the active Li+ cation (n-butyllithium, t-butyllithium and tetramethylguanidinolithium are considered here), and on the solvent employed. X-ray crystallographic studies on a representative compound show that the lithio species exists as a mononuclear, contact ion pair structure, with the triazine ring in a 1,4-dihydro state. On reaction with the Grignard reagent, MeMgCl, this compound gives a methylmagnesiodihydrotriazine, which has also been crystallographically characterised and found to closely resemble its lithio precursor. Ab initio MO calculations on model systems reveal that the 1,4-dihydrotriazine arrangement is energetically preferred to the 1,2-dihydro alternative irrespective of the counterion (Li+ or H+) present. A theoretical investigation of the methanolysis of the lithio species indicates that the formation of an intermediate MeOH complex, with the alcohol attached to a ring N atom and not to Li+, directs the reaction towards ultimate formation of a 1,2-dihydrotriazine.

LanguageEnglish
Pages79-93
Number of pages15
JournalJournal of Organometallic Chemistry
Volume486
Issue number1-2
DOIs
Publication statusPublished - 25 Jan 1995

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Triazines
Nitriles
nitriles
Alcohols
Positive ions
Derivatives
X rays
Atoms
rings
Ions
reagents
Cations
alcohols
X-Rays
cations
products
atoms
ions
x rays
n-butyllithium

Keywords

  • triazine
  • lithium
  • magnesium
  • Ab initio
  • crystal structure
  • organomagnesium compounds
  • lithium compunds
  • ring stacking

Cite this

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title = "Synthetic and theoretical MO calculational studies of lithiotriazine intermediates produced during alkyllithium-induced cyclotrimerisation reactions of organic nitriles, and comparison of their structures with that of a methylmagnesiotriazine derivative",
abstract = "Benzonitrile can be readily cyclotrimerised by treatment with a suitable alkyllithium to give a simple triazine, or to a solvated lithiodihydrotriazine derivative. Which cyclic product dominates depends mainly on the source of the active Li+ cation (n-butyllithium, t-butyllithium and tetramethylguanidinolithium are considered here), and on the solvent employed. X-ray crystallographic studies on a representative compound show that the lithio species exists as a mononuclear, contact ion pair structure, with the triazine ring in a 1,4-dihydro state. On reaction with the Grignard reagent, MeMgCl, this compound gives a methylmagnesiodihydrotriazine, which has also been crystallographically characterised and found to closely resemble its lithio precursor. Ab initio MO calculations on model systems reveal that the 1,4-dihydrotriazine arrangement is energetically preferred to the 1,2-dihydro alternative irrespective of the counterion (Li+ or H+) present. A theoretical investigation of the methanolysis of the lithio species indicates that the formation of an intermediate MeOH complex, with the alcohol attached to a ring N atom and not to Li+, directs the reaction towards ultimate formation of a 1,2-dihydrotriazine.",
keywords = "triazine, lithium, magnesium, Ab initio, crystal structure, organomagnesium compounds, lithium compunds, ring stacking",
author = "D.R. Armstrong and Henderson, {Kenneth. W.} and M. MacGregor and Robert Mulvey and M.J Ross and W. Clegg and P.A. O'Neil",
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TY - JOUR

T1 - Synthetic and theoretical MO calculational studies of lithiotriazine intermediates produced during alkyllithium-induced cyclotrimerisation reactions of organic nitriles, and comparison of their structures with that of a methylmagnesiotriazine derivative

AU - Armstrong, D.R.

AU - Henderson, Kenneth. W.

AU - MacGregor, M.

AU - Mulvey, Robert

AU - Ross, M.J

AU - Clegg, W.

AU - O'Neil, P.A.

PY - 1995/1/25

Y1 - 1995/1/25

N2 - Benzonitrile can be readily cyclotrimerised by treatment with a suitable alkyllithium to give a simple triazine, or to a solvated lithiodihydrotriazine derivative. Which cyclic product dominates depends mainly on the source of the active Li+ cation (n-butyllithium, t-butyllithium and tetramethylguanidinolithium are considered here), and on the solvent employed. X-ray crystallographic studies on a representative compound show that the lithio species exists as a mononuclear, contact ion pair structure, with the triazine ring in a 1,4-dihydro state. On reaction with the Grignard reagent, MeMgCl, this compound gives a methylmagnesiodihydrotriazine, which has also been crystallographically characterised and found to closely resemble its lithio precursor. Ab initio MO calculations on model systems reveal that the 1,4-dihydrotriazine arrangement is energetically preferred to the 1,2-dihydro alternative irrespective of the counterion (Li+ or H+) present. A theoretical investigation of the methanolysis of the lithio species indicates that the formation of an intermediate MeOH complex, with the alcohol attached to a ring N atom and not to Li+, directs the reaction towards ultimate formation of a 1,2-dihydrotriazine.

AB - Benzonitrile can be readily cyclotrimerised by treatment with a suitable alkyllithium to give a simple triazine, or to a solvated lithiodihydrotriazine derivative. Which cyclic product dominates depends mainly on the source of the active Li+ cation (n-butyllithium, t-butyllithium and tetramethylguanidinolithium are considered here), and on the solvent employed. X-ray crystallographic studies on a representative compound show that the lithio species exists as a mononuclear, contact ion pair structure, with the triazine ring in a 1,4-dihydro state. On reaction with the Grignard reagent, MeMgCl, this compound gives a methylmagnesiodihydrotriazine, which has also been crystallographically characterised and found to closely resemble its lithio precursor. Ab initio MO calculations on model systems reveal that the 1,4-dihydrotriazine arrangement is energetically preferred to the 1,2-dihydro alternative irrespective of the counterion (Li+ or H+) present. A theoretical investigation of the methanolysis of the lithio species indicates that the formation of an intermediate MeOH complex, with the alcohol attached to a ring N atom and not to Li+, directs the reaction towards ultimate formation of a 1,2-dihydrotriazine.

KW - triazine

KW - lithium

KW - magnesium

KW - Ab initio

KW - crystal structure

KW - organomagnesium compounds

KW - lithium compunds

KW - ring stacking

U2 - 10.1016/0022-328X(94)05030-F

DO - 10.1016/0022-328X(94)05030-F

M3 - Article

VL - 486

SP - 79

EP - 93

JO - Journal of Organometallic Chemistry

T2 - Journal of Organometallic Chemistry

JF - Journal of Organometallic Chemistry

SN - 0022-328X

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ER -