The Raman spectra of some boron compounds

Summary

The Raman spectra of methyl and ethyl borates have been carefully investigated, and it is found that the Raman frequencies previously reported for these substances require considerable revision. The Raman spectrum of methyl borate in the region of low frequencies shows great similarity to the spectra of the tri-chlorides of phosphorus and arsenic, and this similarity is strikingly brought out by the polarisation characters of the Raman lines. A pyramidal structure is postulated for the B(OCH₃)₃ molecule, the group (OCH₃) being treated as a single unit. The observed and calculated frequencies are in fair agreement. The Raman spectrum of boron tri-bromide is reported for the first time, and consists of two very intense lines and three very weak ones. These are compared with the frequencies of the tri-chloride. Only one line was found in the case of boric acid, which is attributed to the totally symmetrical vibration of the molecule.