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.