MU Chemistry 416 FS97

Articles on 2D-NMR


The Diels-Alder Reaction of 2,40Hexadiene-1-ol with Maleic Anhydride - A Novel Preparation for the Undergraduate Organic Chemistry Laboratory Course. K. F. McDaniel, R. M. Weekly J. Chem. Educ. 1997, 74, 1465-1467.
This is a very nice example to assign structure via the analysis of coupling constants and via the use of a simple homonuclear 2D-COSY.

Determination of the Solution Conformation of 3'-Azido-3'-deoxythymidine-5'-monophosphate (AZTMP) - An Advanced Chemistry and Biochemistry Project using NMR and Molecular-Modeling Studies M. Lee, J. Chem. Educ. 1996, 73, 184-187.
A nice paper that demonstrates the application of 2D-(H,H)-COSY (Figure 2) and of 2D-J-modulated NMR methods (J-values in Table 1). Use is also made of the NOE effect and a difference NOE spectrum is shown in Figure 3. (Note that no NOESY is reported although the authors are using that term. NOESY is a 2D-technique that gives all the NOEs at once.

Symmetry Loss in Piperidine and Morpholine by Nitrogen Coordination A. Flores-Parra, G. Cadenas-Pliego, R. Contreras, N. Zuniga-Villareal,, M. de los Angeles Pas-Sandoval J. Chem. Educ. 1993, 70, 556-559.
Coordination between a N-base (morpholine, piperidine) with a Lewis acid (BH3, (pentadienyl)Mn(CO)3) are studied by NMR. Make sure you understand the spectra of the pure bases (fast ring flipping) and the borane coordinated systems (no ring flipping) and how the 2D-(13C,1H)-COSY (heteronuclear correlated spectroscopy also is called HETCOR) is used to make assignments of H- and C-atoms.

Solution Studies of tert,-Butyllithium/Lithium tert-Butoxide Mixed Aggregates. Observation of a Nonrandom Fluxional Exchange Process in Hexameric Organolithium Compounds G. T. DeLong, D. K. Pannell, M. T. Clarke, R. D. Thomas J. Am. Chem. Soc. 1993, 115, 7013-7014.
This article features a 44-MHz 6Li,1H 2D heteronuclear NOE spectrum (HOESY) of 0.7:1 tert-BuOH/tert-Bu6Li in cyclohexane (3 M in Li) at -20C. The spectrum was used to identify the tert.-butyl and tert.-butoxy groups that are within the same aggregate. Interestingly, it was found that "two of the 6Li hexamer resonances showed correlations to two different butoxide resonances". Take a look at Figure 1 and make sure you understand exactly how this conclusion was reached.

Cation Dynamics and Diffusion in Lithium Orthosilicate: Two-Dimensional Lithium-6 NMR Z. Xu and J. F. Stebbins Science 1995, 270, 1332-1334.
This article demonstrates the use of simple 1D 6Li NMR. In this case, note that the NMR experiment is carried out on a solid sample and the MAS (magic angle spinning) technique is used. This article also is very interesting in that in describes the principle of 2D pure absorption exchange spectroscopy. In the absence of exchange, one gets the regular peaks along the diagonal of a 2D-plot. In the presence of exchange, one finds cross-peaks that indicate the sites that exchange. Doing this with T-dependence lets you determine the thermodynamics of the exchange process. Ain't it cool.