X-ray crystallographic studies and dynamic 1H NMR spectroscopic studies of the novel sodium aza-allyl monomer [PhC(H)NC(H)Ph]Na · PMDETA: A discrete contact ion-pair structure held together by a short NNa bond, and showing close (ortho-Ph)CH ··· Na contacts in both solid state and solution

P C ANDREWS, Robert Mulvey, W CLEGG, D REED

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Abstract

[PhC(H)NC(H)Ph]Na · PMDETA (1) (PMDETA = (Me2NCH2CH2)2NMe), exhibits a contact ion-pair arrangement in the crystal, with the complexed metal cation bound to the nitrogen centre of the aza-allyl fragment (NNa bond length, 2.384(2) Å). Further close contacts exist between the sodium and one ortho-C from each phenyl ring (distances 3.133(4) and 3.166(4) Å). Variable-temperature 1H NMR spectroscopic studies indicate that 1 adopts a remarkably similar structure in tetrahydrofuran-d8 solution. Thus, at −50°C the restricted rotation about each C(ipso)C(benzylic) bond results in the appearance of two distinct resonances each for both the ortho- and meta-H's. From their coalescence temperatures the energy barrier to rotation has been estimated (12.8 kcal mol−1). Evidence that this rigid solution conformation mimics the crystal structure in having short ortho-CH ··· Na distances comes from the exceptionally large chemical shift difference (1.05 ppm) associated with the dual ortho-H signals.
LanguageEnglish
Pages287-297
Number of pages11
JournalJournal of Organometallic Chemistry
Volume386
Issue number3
DOIs
Publication statusPublished - 17 Apr 1990

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Contacts (fluid mechanics)
solid solutions
monomers
Monomers
Sodium
Nuclear magnetic resonance
sodium
X-Rays
Ions
solid state
X rays
nuclear magnetic resonance
Temperature
Energy barriers
Chemical shift
Bond length
tetrahydrofuran
Coalescence
coalescing
chemical equilibrium

Keywords

  • crystallographic studies
  • crystallography
  • crystal structures

Cite this

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title = "X-ray crystallographic studies and dynamic 1H NMR spectroscopic studies of the novel sodium aza-allyl monomer [PhC(H)NC(H)Ph]Na · PMDETA: A discrete contact ion-pair structure held together by a short NNa bond, and showing close (ortho-Ph)CH ··· Na contacts in both solid state and solution",
abstract = "[PhC(H)NC(H)Ph]Na · PMDETA (1) (PMDETA = (Me2NCH2CH2)2NMe), exhibits a contact ion-pair arrangement in the crystal, with the complexed metal cation bound to the nitrogen centre of the aza-allyl fragment (NNa bond length, 2.384(2) {\AA}). Further close contacts exist between the sodium and one ortho-C from each phenyl ring (distances 3.133(4) and 3.166(4) {\AA}). Variable-temperature 1H NMR spectroscopic studies indicate that 1 adopts a remarkably similar structure in tetrahydrofuran-d8 solution. Thus, at −50°C the restricted rotation about each C(ipso)C(benzylic) bond results in the appearance of two distinct resonances each for both the ortho- and meta-H's. From their coalescence temperatures the energy barrier to rotation has been estimated (12.8 kcal mol−1). Evidence that this rigid solution conformation mimics the crystal structure in having short ortho-CH ··· Na distances comes from the exceptionally large chemical shift difference (1.05 ppm) associated with the dual ortho-H signals.",
keywords = "crystallographic studies , crystallography , crystal structures",
author = "ANDREWS, {P C} and Robert Mulvey and W CLEGG and D REED",
year = "1990",
month = "4",
day = "17",
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journal = "Journal of Organometallic Chemistry",
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TY - JOUR

T1 - X-ray crystallographic studies and dynamic 1H NMR spectroscopic studies of the novel sodium aza-allyl monomer [PhC(H)NC(H)Ph]Na · PMDETA: A discrete contact ion-pair structure held together by a short NNa bond, and showing close (ortho-Ph)CH ··· Na contacts in both solid state and solution

AU - ANDREWS, P C

AU - Mulvey, Robert

AU - CLEGG, W

AU - REED, D

PY - 1990/4/17

Y1 - 1990/4/17

N2 - [PhC(H)NC(H)Ph]Na · PMDETA (1) (PMDETA = (Me2NCH2CH2)2NMe), exhibits a contact ion-pair arrangement in the crystal, with the complexed metal cation bound to the nitrogen centre of the aza-allyl fragment (NNa bond length, 2.384(2) Å). Further close contacts exist between the sodium and one ortho-C from each phenyl ring (distances 3.133(4) and 3.166(4) Å). Variable-temperature 1H NMR spectroscopic studies indicate that 1 adopts a remarkably similar structure in tetrahydrofuran-d8 solution. Thus, at −50°C the restricted rotation about each C(ipso)C(benzylic) bond results in the appearance of two distinct resonances each for both the ortho- and meta-H's. From their coalescence temperatures the energy barrier to rotation has been estimated (12.8 kcal mol−1). Evidence that this rigid solution conformation mimics the crystal structure in having short ortho-CH ··· Na distances comes from the exceptionally large chemical shift difference (1.05 ppm) associated with the dual ortho-H signals.

AB - [PhC(H)NC(H)Ph]Na · PMDETA (1) (PMDETA = (Me2NCH2CH2)2NMe), exhibits a contact ion-pair arrangement in the crystal, with the complexed metal cation bound to the nitrogen centre of the aza-allyl fragment (NNa bond length, 2.384(2) Å). Further close contacts exist between the sodium and one ortho-C from each phenyl ring (distances 3.133(4) and 3.166(4) Å). Variable-temperature 1H NMR spectroscopic studies indicate that 1 adopts a remarkably similar structure in tetrahydrofuran-d8 solution. Thus, at −50°C the restricted rotation about each C(ipso)C(benzylic) bond results in the appearance of two distinct resonances each for both the ortho- and meta-H's. From their coalescence temperatures the energy barrier to rotation has been estimated (12.8 kcal mol−1). Evidence that this rigid solution conformation mimics the crystal structure in having short ortho-CH ··· Na distances comes from the exceptionally large chemical shift difference (1.05 ppm) associated with the dual ortho-H signals.

KW - crystallographic studies

KW - crystallography

KW - crystal structures

U2 - 10.1016/0022-328X(90)80001-G

DO - 10.1016/0022-328X(90)80001-G

M3 - Article

VL - 386

SP - 287

EP - 297

JO - Journal of Organometallic Chemistry

T2 - Journal of Organometallic Chemistry

JF - Journal of Organometallic Chemistry

SN - 0022-328X

IS - 3

ER -