Studies of some thermally unstable complexes of group V trihalides with trimethylamine and [2H9]trimethylamine by infrared, Raman, and matrix-isolation Raman spectroscopy, normal co-ordinate analysis, and structural methods

Abstract

Low-temperature i.r. and Raman spectroscopy, ligand deuteriation, and matrix-isolation Raman techniques are used to determine the shapes of the thermally unstable complexes PCl3,NMe3 and PBr3, NMe3. Comparison of the observed and calculated vibrational spectra for the phosphine complexes with the similar data for AsCl3,NMe3(whose crystal structure is known) suggest that they are all isostructural and form pseudotrigonal bipyramidal molecular complexes having a stereochemically active lone pair of electrons in the equatorial plane, which can be considered to be replacing an equatorial chlorine atom in the isoelectronic Group IV complexes MX4, NMe3.