Diborane point group

The structure now universally accepted is that shown in Fig. 1, in which the two bridge hydrogen atoms lie on an axis that is perpendicularly bisected by the plane of the other six atoms. There are three mutually perpendicular twofold axes of symmetry (point group D.,), and the dimensions given are those ob-tained from a recent detailed analysis and conflation (192) of electron-diffraction data (13) with the results of high-resolution infrared spectroscopy (193), as listed in Table I (where the electron-diffraction results for deuterodiborane also appear) Even in the absence of microwave data, we can say that the parameters of diborane are now as accurately known as those for almost any other molecule of con arable size. 

The compound is thermally unstable at room temperature and has an extrapolated boiling point of 27°. Boron exchange is observed with diborane(6) enriched in boron-10 109) and the SH proton exchanges with deuterium chloride 109>. The presence of the mercapto-group in the bridging position is unequivocally established by the boron-11 nmr... 

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