Rayleigh depolarization ratios and molecular polarizability anisotropies of BX 3 (X=F, Cl, Br, I). Comparison of experimental results and ab initio calculations

Abstract

Improved equipment for measurements, at elevated temperatures, of the vapour-phase Rayleigh depolarization ratios of relatively involatile and weakly anisotropic species is described. Analysis of the depolarization ratios in conjunction with the known mean polarizabilities gives values (in 10 −40 C m 2 V −1) of the polarizability anisotropies, Δ α(= α zz − α xx ), of BF 3 (−0.63±0.03), BCl 3 (−3.55±0.11) and BBr 3 (−5.65±0.18); the correlation between the longitudinal polarizability and the cube of the bond length then yields Δ α for BI 3 (−9.0). As well, ab initio calculations of the polarizabilities, and also the quadrupole moments, of BF 3, BCl 3, BBr 3 and BI 3 at the SCF and MP2 levels of theory with the HUZ-SV (+sd) basis set are reported.