11B NMR and Its Uses in Structural Characterization of Boronic Acids and Boronate Esters
11B NMR spectroscopy is frequently used to characterize boron-containing compounds, including boronic acids and boronate esters. A wealth of chemical shift data has been amassed, and selected examples are tabulated here. This chemical shift data can be generalized from representative compounds to other similar structures. 11B NMR data is largely qualitative, but can occasionally be used quantitatively as well. It is often used in conjunction with other techniques such as X-ray crystallography, pH titrations, other spectroscopic methods, and modeling. 11B NMR has been used to identify a change in the hybridization and/or protonation state of boron during a reaction, determine the mode of binding including stoichiometry, and calculate binding affinities. This chapter details examples of this characterization work.