The infrahyphen;red spectrum of diborane has been studied on a prism spectrometer from 400 to 4000 cmmdash;1. Absorption occurs over much of the region investigated. A reliable and complete analysis of the infrahyphen;red and Raman spectra of diborane must await further work, but two alternative tentative analyses of the main features are presented which are in accord with the heat capacity of gaseous diborane from 100 to 300deg;K. One of these analyses is based on the assumed existence of a singlet electronic state at 412 cmmdash;1above the ground state and requires the potential barrier to internal rotation within the molecule to be of the order of 15,000 calories per mole. The alternative analysis assumes that no electronic state lies less than 1600 cmmdash;1above the ground state and requires a potential barrier of about 5000 calories per mole. Both analyses assume an ethanehyphen;like structure for the diborane molecule.
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