Synthetic, structural, mechanistic, and theoretical MO studies of the alkali-metal chemistry of dibenzylamine and its transformation to 1,3-diphenyl-2-azaallyl derivatives

P.C. Andrews, D.R. Armstrong, D.R. Baker, Robert Mulvey, W. Clegg, L. Horsburgh, P.A. O'Neil, D. Reed

Research output: Contribution to journalArticle

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Abstract

Dibenzylamido anions ((PhCH(2)N-) can be transformed into 1,3-diphenyl-2-azaallyl anions ({PhC(H)-N-C(H>Ph}(-)) by the assistance of PMDETA- ((Me(2)NCH(2)CH(2))(2)NMe) complexed Li+, Na+, or K+ cations. The heavier alkali-metal cations give only the trans,trans conformation of the azaallyl anion, in contrast to the lighter Li+ cation, which yields two crystalline conformers, the trans,trans and an unknown species, Ab initio MO geometry optimizations on model Li and Na complexes intimate that it is the relative tightness of the contact ion pair structures which dictates this distinction with Li+ having more influence on the conformation and stability of the anion than Na+, which forms a much looser contact ion pair more akin to the ''free'' anion, On the basis of kinetic H-1 NMR studies, combined with X-ray crystallographic data, the amido --> azaallyl conversion can be explained in terms of a two-step process involving beta-elimiqation of a metal hydride followed by hydride metalation of the produced imine PhCH(2)N=C(H)Ph. This process appears to be initiated by deaggregation of the metallodibenzylamine to an intermediate monomeric structure, accomplished by solvation. The nature and degree of solvation required depend on the particular M(+) cation involved. Three new crystal structures are revealed in the course of this study. All are based on familiar four-membered (N-M)(2) rings, but whereas the sodium complex [{(PhCH(2))(2)NNa.TMEDA}(2)] and the lithium complex [{(PhCH(2))(2)NLi.THF}(2)] are both discrete dimers, unique [{[(PhCH(2))(2)NLi](2).(dioxane)}infinity], isolated as its toluene hemisolvate, is a polymer composed of linked dimeric units and so is the first dibenzylamido alkali-metal species to have an infinitely extended structure.

LanguageEnglish
Pages427-439
Number of pages13
JournalOrganometallics
Volume14
Issue number1
DOIs
Publication statusPublished - Jan 1995

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Alkali Metals
alkali metals
Anions
chemistry
Cations
anions
Derivatives
cations
Solvation
Hydrides
solvation
Conformations
Ions
tightness
metal hydrides
Imines
Toluene
heavy metals
Lithium
Dimers

Keywords

  • organo-lithium compounds
  • molecular structures
  • crystal structure
  • ion pair
  • ray
  • sodium
  • diffraction
  • complexes
  • addition
  • potassium

Cite this

Andrews, P.C. ; Armstrong, D.R. ; Baker, D.R. ; Mulvey, Robert ; Clegg, W. ; Horsburgh, L. ; O'Neil, P.A. ; Reed, D. / Synthetic, structural, mechanistic, and theoretical MO studies of the alkali-metal chemistry of dibenzylamine and its transformation to 1,3-diphenyl-2-azaallyl derivatives. In: Organometallics. 1995 ; Vol. 14, No. 1. pp. 427-439.
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abstract = "Dibenzylamido anions ((PhCH(2)N-) can be transformed into 1,3-diphenyl-2-azaallyl anions ({PhC(H)-N-C(H>Ph}(-)) by the assistance of PMDETA- ((Me(2)NCH(2)CH(2))(2)NMe) complexed Li+, Na+, or K+ cations. The heavier alkali-metal cations give only the trans,trans conformation of the azaallyl anion, in contrast to the lighter Li+ cation, which yields two crystalline conformers, the trans,trans and an unknown species, Ab initio MO geometry optimizations on model Li and Na complexes intimate that it is the relative tightness of the contact ion pair structures which dictates this distinction with Li+ having more influence on the conformation and stability of the anion than Na+, which forms a much looser contact ion pair more akin to the ''free'' anion, On the basis of kinetic H-1 NMR studies, combined with X-ray crystallographic data, the amido --> azaallyl conversion can be explained in terms of a two-step process involving beta-elimiqation of a metal hydride followed by hydride metalation of the produced imine PhCH(2)N=C(H)Ph. This process appears to be initiated by deaggregation of the metallodibenzylamine to an intermediate monomeric structure, accomplished by solvation. The nature and degree of solvation required depend on the particular M(+) cation involved. Three new crystal structures are revealed in the course of this study. All are based on familiar four-membered (N-M)(2) rings, but whereas the sodium complex [{(PhCH(2))(2)NNa.TMEDA}(2)] and the lithium complex [{(PhCH(2))(2)NLi.THF}(2)] are both discrete dimers, unique [{[(PhCH(2))(2)NLi](2).(dioxane)}infinity], isolated as its toluene hemisolvate, is a polymer composed of linked dimeric units and so is the first dibenzylamido alkali-metal species to have an infinitely extended structure.",
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Synthetic, structural, mechanistic, and theoretical MO studies of the alkali-metal chemistry of dibenzylamine and its transformation to 1,3-diphenyl-2-azaallyl derivatives. / Andrews, P.C.; Armstrong, D.R.; Baker, D.R.; Mulvey, Robert; Clegg, W.; Horsburgh, L.; O'Neil, P.A.; Reed, D.

In: Organometallics, Vol. 14, No. 1, 01.1995, p. 427-439.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Synthetic, structural, mechanistic, and theoretical MO studies of the alkali-metal chemistry of dibenzylamine and its transformation to 1,3-diphenyl-2-azaallyl derivatives

AU - Andrews, P.C.

AU - Armstrong, D.R.

AU - Baker, D.R.

AU - Mulvey, Robert

AU - Clegg, W.

AU - Horsburgh, L.

AU - O'Neil, P.A.

AU - Reed, D.

PY - 1995/1

Y1 - 1995/1

N2 - Dibenzylamido anions ((PhCH(2)N-) can be transformed into 1,3-diphenyl-2-azaallyl anions ({PhC(H)-N-C(H>Ph}(-)) by the assistance of PMDETA- ((Me(2)NCH(2)CH(2))(2)NMe) complexed Li+, Na+, or K+ cations. The heavier alkali-metal cations give only the trans,trans conformation of the azaallyl anion, in contrast to the lighter Li+ cation, which yields two crystalline conformers, the trans,trans and an unknown species, Ab initio MO geometry optimizations on model Li and Na complexes intimate that it is the relative tightness of the contact ion pair structures which dictates this distinction with Li+ having more influence on the conformation and stability of the anion than Na+, which forms a much looser contact ion pair more akin to the ''free'' anion, On the basis of kinetic H-1 NMR studies, combined with X-ray crystallographic data, the amido --> azaallyl conversion can be explained in terms of a two-step process involving beta-elimiqation of a metal hydride followed by hydride metalation of the produced imine PhCH(2)N=C(H)Ph. This process appears to be initiated by deaggregation of the metallodibenzylamine to an intermediate monomeric structure, accomplished by solvation. The nature and degree of solvation required depend on the particular M(+) cation involved. Three new crystal structures are revealed in the course of this study. All are based on familiar four-membered (N-M)(2) rings, but whereas the sodium complex [{(PhCH(2))(2)NNa.TMEDA}(2)] and the lithium complex [{(PhCH(2))(2)NLi.THF}(2)] are both discrete dimers, unique [{[(PhCH(2))(2)NLi](2).(dioxane)}infinity], isolated as its toluene hemisolvate, is a polymer composed of linked dimeric units and so is the first dibenzylamido alkali-metal species to have an infinitely extended structure.

AB - Dibenzylamido anions ((PhCH(2)N-) can be transformed into 1,3-diphenyl-2-azaallyl anions ({PhC(H)-N-C(H>Ph}(-)) by the assistance of PMDETA- ((Me(2)NCH(2)CH(2))(2)NMe) complexed Li+, Na+, or K+ cations. The heavier alkali-metal cations give only the trans,trans conformation of the azaallyl anion, in contrast to the lighter Li+ cation, which yields two crystalline conformers, the trans,trans and an unknown species, Ab initio MO geometry optimizations on model Li and Na complexes intimate that it is the relative tightness of the contact ion pair structures which dictates this distinction with Li+ having more influence on the conformation and stability of the anion than Na+, which forms a much looser contact ion pair more akin to the ''free'' anion, On the basis of kinetic H-1 NMR studies, combined with X-ray crystallographic data, the amido --> azaallyl conversion can be explained in terms of a two-step process involving beta-elimiqation of a metal hydride followed by hydride metalation of the produced imine PhCH(2)N=C(H)Ph. This process appears to be initiated by deaggregation of the metallodibenzylamine to an intermediate monomeric structure, accomplished by solvation. The nature and degree of solvation required depend on the particular M(+) cation involved. Three new crystal structures are revealed in the course of this study. All are based on familiar four-membered (N-M)(2) rings, but whereas the sodium complex [{(PhCH(2))(2)NNa.TMEDA}(2)] and the lithium complex [{(PhCH(2))(2)NLi.THF}(2)] are both discrete dimers, unique [{[(PhCH(2))(2)NLi](2).(dioxane)}infinity], isolated as its toluene hemisolvate, is a polymer composed of linked dimeric units and so is the first dibenzylamido alkali-metal species to have an infinitely extended structure.

KW - organo-lithium compounds

KW - molecular structures

KW - crystal structure

KW - ion pair

KW - ray

KW - sodium

KW - diffraction

KW - complexes

KW - addition

KW - potassium

U2 - 10.1021/om00001a059

DO - 10.1021/om00001a059

M3 - Article

VL - 14

SP - 427

EP - 439

JO - Organometallics

T2 - Organometallics

JF - Organometallics

SN - 0276-7333

IS - 1

ER -