Infrared Spectra of Trimethylborane-d9 and Triethylborane-d15

Abstract

The infrared spectra of B(CD₃)₃ and B(C₂D₅)₃ are reported in the 2 to 15 μ range. After minor revisions of a previous frequency assignment for B(CH₃)₃, the force constants obtained from a modified valence force treatment of B(CH₃)₃ have been used to calculate and assign the frequencies of B(CD₃)₃. This assignment is consistent with frequency values predicted from a study of other methyl‐deuterated compounds. Agreement with the Teller‐Redlich product rule is fair. An interesting and perhaps unexpected feature is the upward shift of the B–C asymmetric stretching frequency upon deuteration; the correctness of the assignment of that vibration was verified by use of B¹⁰(CD₃)₃. In the latter part of this article, the observed bands of B(C₂D₅)₃ are assigned.