Nielson, AJ; Schwerdtfeger, P; Waters, JM
Thermalisation of TiCl4 and phenol (1:1) in toluene gave
[TiCl3(OC6H5)] 1. The more soluble complex [TiCl3(OC6H4CMe3-4)] 2 is monomeric in benzene and
reacts with 4,4'-dimethyl-2,2'-bipyridyl (dmbipy) to give mer-[TiCl3(OC6H4CMe3-4)(dmbipy)] 3
and the disproportionation product [TiCl2(OC6H4CMe3-4)(2)(dmbipy)]. The complex [TiCl3(OC6H2Me3-
2,4,6)] 4 is monomeric in benzene whereas [TiCl3(OC6H3Pr2i-2,6)] 5 partially disproportionates in
solution into [TiCl2(OC6H3Pr2i-2,6)(2)] and reacts with dmbipy to give mer-[TiCl3(OC6H3Pr2i-2,6)
(dmbipy)] 6 and [TiCl2(OC6H3Pr2i-2,6)(2)(dmbipy)]. Thermalisation of 2,6-di-tert-butyl-4-
methylphenol and TiCl4 in toluene caused debutylation but [TiCl3{OC6H2(CMe3)(2)-2,6-Me-4}] 7
forms in light petroleum (bp range 40-60 degrees C). Complex 7 is monomeric in benzene and does
not form adducts with dmbipy or other sigma donors. A crystal structure determination of 7 showed
a monomer with distorted tetrahedral co-ordination, a Ti-O bond length of 1.750(2) Angstrom and
Ti-Cl bonds longer than in TiCl4 but shorter than in [TiCl3(C5H5)] or [TiCl3{C5H3(CMe3)(2)-1,3}].
2,4,6-Tri-tert-butylphenol debutylates when thermalised with TiCl4 in toluene giving [TiCl3
{OC6H4(CMe3)(2)-2,4} ] 8. The complexes [TiCl3{OC6H2(CMe3)(2)-2,6-OMe-4}] 9, [TiCl3(OC6H3CMe3-2-
Me-4)] 10, [TiCl3(OC6H4Ph-2)] 11 and the 1-naphthoxide complex [TiCl3(OC10H7)] 12 were also
prepared. Density functional calculations performed on the models 4 and [TiCl3(OMe)] showed both
lone pairs on oxygen donate electron density to titanium but O(2p)-to-C=C (pi*) donation weakens
the Ti-O interaction in the phenoxide complex; Cl(2p)-to-Ti(3d) donation is much reduced in the
methoxide complex. The system [TiCl3(OC6H4CMe3-4)]/AlMe3 is 280 times more active than [TiCl3Cp]
(Cp=cyclopentadienyl)/AlMe3 for low pressure (6 psi) ethylene polymerisation but 1/3 less active
than TiCl4/AlMe3.