121Sb-Mössbauer-spektroskopische und strukturchemische Untersuchungen an Kronenetherkomplexen SbX3(15-Krone-5) mit X = F, Cl, Br, I. Eine Analyse der Orbitalbesetzungszahlen / 121Sb-Mössbauer-Spectroscopic and Structural Investigations on Crown Ether Complexes SbX3(15-Crown-5) with X = F, Cl, Br, I. A Population Analysis

Abstract

The crown ether complexes SbX3(15-crown-5) with X = F, Cl, Br, and I have been prepared by reactions of 15-crown-5 with the corresponding antimony trihalides in acetonitrile solutions. The compounds were characterized by IR spectroscopy as well as by 121Sb-Mössbauer spectroscopy. A method of orbital population analysis utilizing both Mössbauer isomer shifts and quadrupole coupling has been developed for Sb(III) antimony halides and their crown ether complexes. SbF3(15-crown-5) was also characterized by an X-ray structure determination: Space group P21/n, Z = 4, 3628 observed unique reflexions, R = 0.032. Lattice dimensions at 19 °C: a = 891.54(6), b = 1277.26(6), c = 1277.66(7) pm, β = 95.029(4)°. The complex has a molecular structure in which the antimony atom is surrounded by three F-atoms with mean bond lengths of 192.4 pm and by the five oxygen atoms of the crown ether molecule with mean bond lengths of 293.9 pm.