Knowledge Bank

Proton magnetic resonance spectra of several of the boranes have been studied and have, in general, yielded interesting results. However, the coupling between the nuclear spins of the $B11$ nuclei and the protons results in an overlapping multiplet structure of the lines which has complicated the assignments. Experiments have been performed in which the $B11$ nuclei were excited at their resonant frequency while the proton magnetic resonance spectra were obtained in the usual way. By this means, it has been possible to collapse the multiplet structures of the spectra and to verify the assignments as they would apply in the unsplit case. Spectra of diborane, borohydride ions, and pentaborane are offered as examples of the application of this technique.