Direct electrochemical synthesis of neutral and anionic chloro- and bromo-complexes of titanium, zirconium, and hafnium

Electrochemical oxidation of titanium, zirconium, or hafnium(IV) in the presence of a solution of chlorine or bromine (X) in acetonitrile (L) leads to direct synthesis of MX 4 L 2 species in good yield. These compounds are easily transformed into other neutral adducts. On addition of tetraalkylammonium salts to the solution phase, the products are the salts (R 4 N)MCl 5 or (R 4 N) 2 MBr 6 , except that with titanium Et 4 NTiBr 4 was also formed under some conditions. The advantages of this method are discussed, and a possible reaction mechanism proposed.