Interaction of titanium(III) zwitterionic complex Cp[η5-C5H4B(C6F5)3]Ti with organic halides:: Synthesis and X-ray crystal monohalides catalytic activity structure determination of zwitterionic titanocene Cp[η5-C5H4B(C6F5)3]TiX (X = Cl, Br) and their in the ring-opening polymerization of ε-caprolactone

The reaction of the titanium(III) zwitterionic Complex Cp[eta(5)-C5H4B(C6F5)(3)]Ti (1) with CCl4 at 20 degrees C under Ar results in the formation of hexachloroethane and the zwitterionic titanocene monochloride Cp[eta(5)-C5H4B(C6F5)(3)]TiCl (3) containing a B(C6F5)(3) Moiety in the eta(5)-cyclopentadienyl ring. Under similar conditions, the reaction of 1 with 1,2-dibromoethane affords ethylene and the corresponding zwitterionic monobromide Cp[eta(5)-C5H4B(C6F5)(3)]TiBr (4). An X-ray diffraction study of 3 and 4 revealed the presence of a coordinative bond between the ortho-fluorine atom of one of the C6F5 substituents and the positively charged titanium centre. In the interaction of 1 with n-propyl iodide at 20 degrees C. titanocene diiodide, B(C6F5)(3) and propylene are produced. The mechanism of this interesting reaction is discussed. The synthesized zwitterions 3 and 4 are able to catalyze the ring-opening polymerization of epsilon-capro-lactone in a toluene solution and in bulk. The highest activity in this process is exhibited by 3. The first X-ray diffraction study of CP2TiI2, has been carried out. (c) 2005 Elsevier B.V. All rights reserved.