RAYLEIGH DEPOLARIZATION RATIOS AND MOLECULAR POLARIZABILITY ANISOTROPIES OF BX3 (X = F, CL, BR, I) - COMPARISON OF EXPERIMENTAL RESULTS ANDAB-INITIO CALCULATIONS

Improved equipment for measurements, at elevated temperatures, of the vapour-phase Rayleigh depolarization ratios of relatively involatile a nd weakly anisotropic species is described. Analysis of the depolariza tion ratios in conjunction with the known mean polarizabilities gives values (in 10(-40) Cm-2 V-1) of the polarizability anisotropies, Delta alpha(= alpha(zz) - alpha(xx)), of BF,(- 0.63 +/- 0.03), BCl3(- 3.55 +/- 0.11) and BBr3 (- 5.65 +/- 0.18); the correlation between the long itudinal polarizability and the cube of the bond length then yields De lta alpha for BI,(- 9.0). As well, ab initio calculations of the polar izabilities, and also the quadrupole moments, of BF3, BCl3, BBr3 and B I3 at the SCF and MP2 levels of theory with the HUZ-SV(+ sd) basis set are reported. (C) 1998 Elsevier Science B.V. All rights reserved.