Vibrational spectroscopic study of trimethylarsine–boron trihalide adducts

Abstract

The vibrational spectra of AsR₃·¹⁰BX₃(R = CH₃ or CD₃; X = Cl or Br) and AsR₃·ⁿBX₃(R = CH₃ or CD₃; X = Cl, Br, or l; n = natural abundance) are reported. The BAs stretching frequencies are assigned between 640 and 740 cm^–1, and the calculated force constants (2.84, 2.26, and 1.70 mdyn A^–1) show that the BAs bond strength decreases for the adducts in the sequence Bl₃ > BBr₃ > BCl₃. The order of BAs bond strength is the same as that of the adduct stabilities as determined by calorimetry.