Computation of through-space NMR shielding effects in aromatic ring π-stacked complexes

Martin, Ned H.; Floyd, Ruth M.; Woodcock, H. Lee; Huffman, Scott W.; Lee, Chang-Kiu

doi:10.1016/j.jmgm.2007.10.004

Cited by 16 publications

(10 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Structures of the five-membered ring heterocyclic compounds in the study. 1 Previous calculations [28] have shown that basis set superposition error, as measured by the counterpoise method of Boys and Bernardi [34], has a negligible effect on shielding values. BSSE is typically no greater than 0.05 ppm.…”

Section: Resultsmentioning

confidence: 99%

“…We have reported the results of GIAO-HF calculations to calculate through-space NMR shielding effects on a probe molecule and to map the resulting through-space NMR shielding increments in aromatic ring p-stacked complexes [28]. More recently the computed shielding effects of linear polycyclic aromatic hydrocarbons (PAHs) [29] and the relationship between the computed shielding effects and the extent of aromaticity have been reported.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Computed NMR shielding increments over unsaturated five-membered ring heterocyclic compounds as a measure of aromaticity

Martin

Rowe

Pittman

2009

Journal of Molecular Graphics and Modelling

Self Cite

View full text Add to dashboard Cite

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Computed NMR shielding increments over unsaturated five-membered ring heterocyclic compounds as a measure of aromaticity

Martin

Rowe

Pittman

2009

Journal of Molecular Graphics and Modelling

Self Cite

View full text Add to dashboard Cite

“…A series of single point GIAO calculations was performed in Gaussian 03 [37] on a PQS Linux cluster on these supramolecules using the same method and basis set, moving the H 2 probe in 0.5 Å increments in both the X and Y directions in separate calculations. Previous calculations [38] have shown that basis set superposition error, as measured by the counterpoise method of Boys and Bernardi [39], introduces a negligible effect on shielding values; BSSE is typically no greater than 0.05 ppm. Also, the difference between the shielding values obtained using single point calculations and constrained geometry-optimized calculations is also negligible [31].…”

Section: Computational Sectionmentioning

confidence: 98%

Computed NMR Shielding Effects over Fused Aromatic / Antiaromatic Hydrocarbons

Martin¹,

Teague²,

Mills³

2010

Symmetry

Self Cite

View full text Add to dashboard Cite

Through-space isotropic NMR shielding values of a perpendicular diatomic hydrogen probe moved in a 0.5 Å grid 2.5 Å above several polycyclic aromatic/antiaromatic ring and aromatic/aromatic hydrocarbons were computed with Gaussian 03 at the GIAO HF/6-31G(d,p) level. Combinations of benzene fused with cyclobutadiene, with the tropylium ion, and with the cyclopentadienyl anion were investigated. Subtraction of the isolated H 2 isotropic value gave shielding increments (∆σ), which, when plotted against Cartesian coordinates of the probe over each hydrocarbon, gave representations of threedimensional isotropic shielding increment surfaces. The results are related to the degree of bond length alternation, the extent of π electron delocalization, and (for the ions) the NPA charge distribution. The shielding increment data are compared to NICS(1) values computed at the same level; both indicate the degree of aromaticity or antiaromaticity of the component rings.

show abstract

“…3.96 Å in the solid state). [26][27][28] This is in remarkable contrast to the 1 H NMR spectra observed for the lithiated aryl imines (Li-L 3-8 ). For the lithiated aryl imines, in all cases the two protons of the methylenedioxy unit were found to be equivalent on the solution NMR timescale.…”

Section: Resultsmentioning

confidence: 99%

Structural Characterization of Novel ortho‐Lithiated Imines

2010

View full text Add to dashboard Cite

Keywords: Lithiation / Ligand design / Schiff bases / Imines / Coordination polymer ortho-Metallated imines are commonly used as ligands for late transition metals. Unfortunately, not all metals, such as titanium, zirconium, and niobium, can undergo the necessary oxidative addition reactions to form the desired ortho-metallated complexes directly. Therefore, a synthetic methodology allowing easy access to this binding mode from simple early transition metal halides via an ortho-lithiated imine precursor is desirable. ortho-Lithiation of benzylamines and other systems has been well studied; in contrast, that of imines is poorly developed. However, inclusion of a 3,4-methylenedioxy group on phenyl imines allows for straightforward lithiation and simple isolation of the ortho-lithiated imines. NMR spectroscopy and single-crystal X-ray diffraction allowed for the structural elucidation of the clustering in these lithium complexes. It has been determined that the nature of the im-

show abstract

Computation of through-space NMR shielding effects in aromatic ring π-stacked complexes

Cited by 16 publications

References 22 publications

Computed NMR shielding increments over unsaturated five-membered ring heterocyclic compounds as a measure of aromaticity

Computed NMR shielding increments over unsaturated five-membered ring heterocyclic compounds as a measure of aromaticity

Computed NMR Shielding Effects over Fused Aromatic / Antiaromatic Hydrocarbons

Structural Characterization of Novel ortho‐Lithiated Imines

Contact Info

Product

Resources

About