Determination of the molecular structure and absolute configuration of (R)-tris(trifluoroacetato)antimony(III)

Abstract

Crystals of the title compound are colourless and crystallise in the cubic space group P4₃32 with a= 13.840(3)Å and Z= 8. The crystal structure has been solved by a combination of heavy-atom and direct methods and refined by weighted, anisotropic, full-matrix, least squares to a conventional R value of 0.0227 using 485 independent observed reflections measured on a four-circle diffractometer. The absolute configuration has been determined from a significance test applied to the ratio of the Hamilton-weighted R factors for the two enantiomorphs after the effects of anomalous dispersion had been included. The molecule is discrete and the geometry on Sb is pyramidal with crystallographic C₃ symmetry. The trifluoroacetato-groups function as unidentate ligands [Sb–O 2.043(4)Å and O–Sb–O 84.92(16)°]. The i.r. and Raman spectra of the solid are reported and shown to be consistent with the structure.