Properties and Structure
TiCl4 is a dense, colourless distillable liquid, although crude samples may be yellow or even red-brown. It is one of the rare transition metal halides that is a liquid at room temperature, VCl4 being another example. This property reflects the fact that TiCl4 is molecular; that is, each TiCl4 molecule is relatively weakly associated with its neighbours. Most metal chlorides are polymers, wherein the chloride atoms bridge between the metals. The attraction between the individual TiCl4 molecules is weak, primarily van der Waals forces, and these weak interactions result in low melting and boiling points, similar to those of CCl4.
Ti4+ has a "closed" electronic shell, with the same number of electrons as the inert gas argon. The tetrahedral structure for TiCl4 is consistent with its description as a d0 metal center (Ti4+) surrounded by four identical ligands. This configuration leads to highly symmetrical structures, hence the tetrahedral shape of the molecule. TiCl4 adopts similar structures to TiBr4 and TiI4; the three compounds share many similarities. TiCl4 and TiBr4 react to give mixed halides TiCl4 -xBrx, where x = 0, 1, 2, 3, 4. Magnetic resonance measurements also indicate that halide exchange is also rapid between TiCl4 and VCl4.
TiCl4 is soluble in toluene and chlorocarbons, as are other non-polar species. Evidence exists that certain arenes form complexes of the type +. TiCl4 reacts exothermically with donor solvents such as THF to give hexacoordinated adducts. Bulkier ligands (L) give pentacoordinated adducts TiCl4L.
Read more about this topic: Titanium Tetrachloride
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