Molecular complexes of triphenylphosphine Oxide and triphenylarsine oxide with antimony(III) and bismuth(III) halides. Vibrational spectra and structures

Abstract

Nine new complexes are prepared (SbBr 3·2(C 6H 5) 3PO, Sbl 3·2(C 6H 5) 3PO, BiCl 3·3(C 6H 5) 3PO, SbBr 3·2(C 6H 5) 3AsO, [SbBr 2·4(C 6H 5) 3AsO] Br, [SbI 2·3(C 6H 5)3AsO]I, BiCl 3·2(C 6H 5) 3AsO, BiBr 3· 3(C 6H 5) 3AsO and 2BiI 3·3(C 6H 5) 3AsO) and their molecular structure and the structure of the complexes SbCl 3·2(C 6H 5) 3PO, BiBr 3·2(C 6H 6)3PO, BiI 3· 2(C 6H 5) 3PO and SbCl 3·2(C 6H 5) 3AsO discussed on the basis of vibrational spectra. It is shown that the mean shifts of ν(PO) and ν(AsO) are proportional to the Lewis acidity and basicity of the components. taking into account the configuration and the number of ligands. The structure of the bridging halogen bonds is discussed and caution is suggested in deducing the stereochemical inactivity of the electron lone pair of antimony(III) and bismuth(III) in polynucluear complexes from crystal structure data only. the degenerate deformation vibrational of the PO and asO bonds in the far infrared spectra of the free oxo-bases are located and the 1050–1150 cm −1 region in triphenylphosphine oxide in reassigned.