Antimony-121 Mössbauer spectra of some heterocyclic cis-diorganoantimony(V) compounds

Abstract

The ¹²¹Sb Mössbauer spectra are reported for a series of heterocyclic cis-diorganoantimony(V) compounds of general formulae [NMe₄][SbR₂Cl₄] and SbR₂Cl₃. The asymmetry parameter of the electric-field-gradient (e.f.g.) tensor is large in all the tetrachloro-compounds because of distortion of the molecule by the formation of the heterocyclic ring. A point-charge model has been formulated in terms of the C–Sb–C bond angle and the partial-field-gradient contributions of the ligands; this model provides a satisfactory correlation between the e.f.g. parameters and the expected stereochemistry. Similar calculations have been carried out for the trichloro-compounds.