Infrared Spectra of Partially Deuterated Diboranes

Abstract

Infrared spectra, in the 2 to 15 μ range, of equilibrium mixtures of various proportions of B2H6 and B2D6 are reported. These mixtures contain twenty-one different species (represented by seven molecular formulas ranging from B2H6 to B2D6), which exist in equilibrium with one another and cannot be separated by chemical or physical means. However, the spectra of the individual formula groups B2D5H and B2H5D were obtained by spectroscopically compensating for other species present in the equilibrium mixtures. An assignment of the observed and unobserved fundamental frequencies of the four molecules represented by the two formulas is made with the help of previously published data on B2H6 and B2D6 and by application of the noncrossing rule and the product and sum rules. Comparisons with published spectra of partially deuterated ethylenes and dimethylaminodiborane support these assignments.