Alkali metal-1-azaallyl complexes: X-ray crystallographic, NMR spectroscopic and ab initio calculational studies

D R Armstrong, W Clegg, L Dunbar, S T Liddle, M MacGregor, Robert Mulvey, D Reed, S A Quinn

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

A series of alkali metal-1-azaallyl complexes, [{CH3CH2CH2C(H)C(Bu-t)N(H)Li . HMPA}(2)], 1, [{CH3CH2CH2C(H)C(Bu-t)N(H)Na . 2HMPA}(2)] 2 and [{CH2C(Bu-t)N(H)Li . HMPA}(2)] 3, has been synthesised by treating each appropriate metal alkyl reagent (n-butyllithium, n-butylsodium or methyllithium, respectively) with tert-butyl cyanide in the presence of the Lewis base HMPA [hexamethylphosphoramide, (Me2N)(3)P=O]. X-Ray crystallographic studies have established that each structure is dimeric and built around a precisely or approximately centrosymmetric rhomboidal (N-M)(2) ring. However, the nature of the azaallyl-metal bonding differs with 1 and 2 displaying a terminal eta(1)-N arrangement, while 3 displays a chelating eta(3)-NCC arrangement. H-1 and C-13 NMR spectroscopic studies suggest that these distinct bonding modes an retained in [H-2(8)]toluene solution. Long-range ((4)J) "W" coupling (2.4 Hz) is observed for 3 between the NH and one of the alpha-CH2 protons, consistent with the trans orientation of the NH and Cchemical anionC linkages seen in the solid state. The preference for this geometry is confirmed by ab initio MO calculations on models of 3, which examine the energetics of the ketimide-azaallyl isomerism involved in the formation of 1-3.

LanguageEnglish
Pages3431-3436
Number of pages6
JournalJournal of the Chemical Society, Dalton Transactions
Issue number20
DOIs
Publication statusPublished - 21 Oct 1998

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Hempa
Alkali Metals
Nuclear magnetic resonance
X rays
Metals
Lewis Bases
Toluene
Cyanides
Chelation
Protons
Display devices
Geometry

Keywords

  • molecular orbital methods
  • basis sets
  • aza-allyl
  • metal
  • LITHIUM
  • ions
  • crystal structures

Cite this

Armstrong, D R ; Clegg, W ; Dunbar, L ; Liddle, S T ; MacGregor, M ; Mulvey, Robert ; Reed, D ; Quinn, S A . / Alkali metal-1-azaallyl complexes: X-ray crystallographic, NMR spectroscopic and ab initio calculational studies. In: Journal of the Chemical Society, Dalton Transactions. 1998 ; No. 20. pp. 3431-3436.
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title = "Alkali metal-1-azaallyl complexes: X-ray crystallographic, NMR spectroscopic and ab initio calculational studies",
abstract = "A series of alkali metal-1-azaallyl complexes, [{CH3CH2CH2C(H)C(Bu-t)N(H)Li . HMPA}(2)], 1, [{CH3CH2CH2C(H)C(Bu-t)N(H)Na . 2HMPA}(2)] 2 and [{CH2C(Bu-t)N(H)Li . HMPA}(2)] 3, has been synthesised by treating each appropriate metal alkyl reagent (n-butyllithium, n-butylsodium or methyllithium, respectively) with tert-butyl cyanide in the presence of the Lewis base HMPA [hexamethylphosphoramide, (Me2N)(3)P=O]. X-Ray crystallographic studies have established that each structure is dimeric and built around a precisely or approximately centrosymmetric rhomboidal (N-M)(2) ring. However, the nature of the azaallyl-metal bonding differs with 1 and 2 displaying a terminal eta(1)-N arrangement, while 3 displays a chelating eta(3)-NCC arrangement. H-1 and C-13 NMR spectroscopic studies suggest that these distinct bonding modes an retained in [H-2(8)]toluene solution. Long-range ((4)J) {"}W{"} coupling (2.4 Hz) is observed for 3 between the NH and one of the alpha-CH2 protons, consistent with the trans orientation of the NH and Cchemical anionC linkages seen in the solid state. The preference for this geometry is confirmed by ab initio MO calculations on models of 3, which examine the energetics of the ketimide-azaallyl isomerism involved in the formation of 1-3.",
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Alkali metal-1-azaallyl complexes: X-ray crystallographic, NMR spectroscopic and ab initio calculational studies. / Armstrong, D R ; Clegg, W ; Dunbar, L ; Liddle, S T ; MacGregor, M ; Mulvey, Robert; Reed, D ; Quinn, S A .

In: Journal of the Chemical Society, Dalton Transactions, No. 20, 21.10.1998, p. 3431-3436.

Research output: Contribution to journalArticle

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T1 - Alkali metal-1-azaallyl complexes: X-ray crystallographic, NMR spectroscopic and ab initio calculational studies

AU - Armstrong, D R

AU - Clegg, W

AU - Dunbar, L

AU - Liddle, S T

AU - MacGregor, M

AU - Mulvey, Robert

AU - Reed, D

AU - Quinn, S A

PY - 1998/10/21

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N2 - A series of alkali metal-1-azaallyl complexes, [{CH3CH2CH2C(H)C(Bu-t)N(H)Li . HMPA}(2)], 1, [{CH3CH2CH2C(H)C(Bu-t)N(H)Na . 2HMPA}(2)] 2 and [{CH2C(Bu-t)N(H)Li . HMPA}(2)] 3, has been synthesised by treating each appropriate metal alkyl reagent (n-butyllithium, n-butylsodium or methyllithium, respectively) with tert-butyl cyanide in the presence of the Lewis base HMPA [hexamethylphosphoramide, (Me2N)(3)P=O]. X-Ray crystallographic studies have established that each structure is dimeric and built around a precisely or approximately centrosymmetric rhomboidal (N-M)(2) ring. However, the nature of the azaallyl-metal bonding differs with 1 and 2 displaying a terminal eta(1)-N arrangement, while 3 displays a chelating eta(3)-NCC arrangement. H-1 and C-13 NMR spectroscopic studies suggest that these distinct bonding modes an retained in [H-2(8)]toluene solution. Long-range ((4)J) "W" coupling (2.4 Hz) is observed for 3 between the NH and one of the alpha-CH2 protons, consistent with the trans orientation of the NH and Cchemical anionC linkages seen in the solid state. The preference for this geometry is confirmed by ab initio MO calculations on models of 3, which examine the energetics of the ketimide-azaallyl isomerism involved in the formation of 1-3.

AB - A series of alkali metal-1-azaallyl complexes, [{CH3CH2CH2C(H)C(Bu-t)N(H)Li . HMPA}(2)], 1, [{CH3CH2CH2C(H)C(Bu-t)N(H)Na . 2HMPA}(2)] 2 and [{CH2C(Bu-t)N(H)Li . HMPA}(2)] 3, has been synthesised by treating each appropriate metal alkyl reagent (n-butyllithium, n-butylsodium or methyllithium, respectively) with tert-butyl cyanide in the presence of the Lewis base HMPA [hexamethylphosphoramide, (Me2N)(3)P=O]. X-Ray crystallographic studies have established that each structure is dimeric and built around a precisely or approximately centrosymmetric rhomboidal (N-M)(2) ring. However, the nature of the azaallyl-metal bonding differs with 1 and 2 displaying a terminal eta(1)-N arrangement, while 3 displays a chelating eta(3)-NCC arrangement. H-1 and C-13 NMR spectroscopic studies suggest that these distinct bonding modes an retained in [H-2(8)]toluene solution. Long-range ((4)J) "W" coupling (2.4 Hz) is observed for 3 between the NH and one of the alpha-CH2 protons, consistent with the trans orientation of the NH and Cchemical anionC linkages seen in the solid state. The preference for this geometry is confirmed by ab initio MO calculations on models of 3, which examine the energetics of the ketimide-azaallyl isomerism involved in the formation of 1-3.

KW - molecular orbital methods

KW - basis sets

KW - aza-allyl

KW - metal

KW - LITHIUM

KW - ions

KW - crystal structures

U2 - 10.1039/A805523H

DO - 10.1039/A805523H

M3 - Article

SP - 3431

EP - 3436

JO - Journal of the Chemical Society, Dalton Transactions

T2 - Journal of the Chemical Society, Dalton Transactions

JF - Journal of the Chemical Society, Dalton Transactions

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