Ronald Wagner

ACCORD-HMBC : A SUPERIOR TECHNIQUE FOR STRUCTURAL ELUCIDATION

The standard gradient selected HMBC pulse sequence was modified. With the ACCORDION principle a range of spin coupling constants is sampled which gives a complete set of long‐range C,H connectivities. A better low‐pass filter allows GARP 13C decoupling.

HETERONUCLEAR EDITED GRADIENT SELECTED 1D AND 2D NOE SPECTRA : DETERMINATION OF THE NOE EFFECT BETWEEN CHEMICALLY EQUIVALENT PROTONS

With gradient selected HSQC‐NOESY spectra it is possible to detect the NOE effect between protons which have the same chemical shift either due to symmetry or due to accidental overlap. The discrimination of the equivalent sites is achieved by allowing one site to couple with 13C in natural abundance. The suppression of unwanted signals is performed with pulse field gradient selection. Both 2D and selective 1D methods are shown.

Two-Dimensional Correlation Spectroscopy by Scalar Couplings: A Walk Through the Periodic Table

A review of 2D correlation NMR spectroscopy is presented which excludes the standard cases of 1H,1H, 13C,1H, 15N,1H and 13C,13C applications. Instead, emphasis is laid on the inclusion of seldom used heteronuclei. 1H,X, X,X and X,Y correlations are summarized, the dominant experimental techniques are described and the chemical applications of these 2D correlations are outlined.

SPIN LOCK VERSUS INEPT AND DEPT POLARIZATION TRANSFER FOR 29Si NMR SPECTROSCOPY

Abstract The 29Si NMR spectra of a variety of silicon compounds were recorded with prior polarization transfer via spin locking of the protons. The results were compared with the traditional INEPT and DEPT protocols, and it is shown that, under optimized conditions, spin lock polarization transfer yields 29Si NMR spectra with an increase in signal to noise ratio by a factor of 1.6 in the average. The advantages and disadvantages of the methods employed are discussed.