121Sb Isomer Shifts in Antimony Halides

Abstract

Mössbauer spectra of 121Sb in all the binary antimony halides have been obtained, as well as in cubic Sb2O3. The isomer shifts relative to the 121SnO2 source are − 11.3 mm/sec (Sb2O3), − 13.8 (SbCl3), − 13.9 (SbBr3), − 15.9 (SbI3), − 14.6 (SbF3), + 2.2 (SbF5), and − 3.12 (SbCl5). Quadrupole splittings were obtained for most of the antimony(III) compounds. The linear variation of isomer shift with ligand–metal electronegativity difference for Sb2O3, SbCl3, SbBr3 and SbI3 is interpreted as due to a constant s character in the ligand–metal bonds. The SbF3 does not obey this relationship due to its radically different geometry.