Characterizing the BP Stretching Vibration in Phosphorus‐Substituted Phosphine Boranes

The experimental Raman spectra of three phosphorus‐substituted phosphine boranes with bulky hydrocarbon substituents are presented and compared to the results of electronic structure computations by using the M06‐2X method and the 6‐311G(2df, 2pd) basis set. Total‐energy distributions (TEDs) are calculated to describe the degree of mixing of the dative‐bond stretching vibration with other simple internal coordinates. This level of theory is found to accurately reproduce the B?P stretching frequency in all three crystalline solids. The Raman spectra of five smaller B?P‐containing molecules, including BH₃PH₃, are also simulated at this level of theory and compared to previous experimental results.