Fluoro-complexes of the Group IVA elements: metal–halogen vibrational frequencies

Abstract

Titanium tetrafluoride and tetrachloride react with 2,2′-bipyridyl (bipy), 1,10-phenanthroline (phen), and o-phenylenebisdimethylamine (diamine) to yield the complexes TiX₄, bipy, TiX₄phen, and (TiX₄)₂,diamine (X = F or Cl). Zirconium tetrafluoride reacts with bipyridyl to yield the complex ZrF₄,2bipy, whereas zirconium and hafnium tetrachlorides react with this ligand to yield complexes with the stoicheiometry MCl₄,1 ½ bipy (M = Zr or Hf). Zirconium tetrachloride also yields a complex of this stoicheiometry with the diamine, but the latter reacts with stannic chloride to yield the complex SnCl₄,diamine. Physical measurements on the complexes are severely curtailed by their low solubilities in non-disruptive solvents, but it is believed that whereas titanium complexes involve only six-co-ordinate titanium atoms, the zirconium and hafnium complexes may involve eight-co-ordinate metal atoms.

The infrared spectra of complexes have been recorded as well as those of other already characterised adducts of titanium and zirconium tetrafluoride, in order to establish the regions in which titanium–fluorine and zirconium–fluorine stretching frequencies occur. These are 550–670 and 453–570 cm.^–1, respectively. Fluorine–tatanium–fluorine bending modes occur in the region 254–311 cm.^–1.