11B Double Quantum - Single Quantum Correlation Spectroscopy
The
2D 13C INADEQUATE method provides double quantum - single quantum (DQ/SQ) correlations and enables one to determine the carbon - carbon skeleton of small organic molecules. The method is quite insensitive for 13C since the natural abundance of 13C is only 1.1% and the chance of having two adjacent 13C nuclei is only 1 in 8264. For spins other than 13C, for which the natural abundance is high, one expects the sensitivity of DQ/SQ correlation spectroscopy to be much higher. 11B has a natural abundance of 80.42% and the chance of having two adjacent 11B nuclei in compounds with boron-boron bonds is 1 in 1.55. 11B NMR spectra are often sufficiently broad due to efficient quadrupolar relaxation such that homonuclear 11B - 11B J coupling is unresolved however the T2's are long enough to allow the collection of
2D 11 B COSY and 2D DQ/SQ data. The figure below shows the 2D 11B DQ/SQ correlation spectrum of
ortho-carborane. The 11B bonding connectivity can be determined easily from the spectrum.
Source:
University of Ottawa NMR Facility Blog