Some substitution reactions of ligands coordinated to the bis(cyclopentadienyl)titanium moiety, the X-ray crystal structure of Ti(η 5-C 5H 5) 2(OPh) 2 and an assessment of the anti-tumour activity of some cyclopentadienyl titanium compounds

Abstract

The new complexes Ti(η 5-C 5H 5)Cl(OC 6H 4NH 2-3) 2, Ti(η 5-C 5H 5)Cl(O 2CPh) 2, Ti(η 5-C 5H 5) 2(O 2C(S)C 6H 4-1,2), Ti(η 5-C 5H 5) 2Cl(SC 6H 4OH-4), Ti(η 5-C 5H 5) 2(OC 6H 4NH 2-3) 2 and Ti(η 5-C 5H 5) 2Cl(OC 6H 4Z) (Z = NO 2-2, NO 2-3, NO 2-4, NH 2-3) have been synthesized. The free amine group in Ti(η 5-C 5H 5) 2Cl(OC 6H 4NH 2-3) reacts with RCl [R = MeCO, PhCO, (OCCO) 1/2, Br(CH 2) 3CO] in the presence of base to give Ti(η 5-C 5H 5) 2Cl(R) but, in the absence of base, PhCOCl reacts to give PhCONHC 6H 4OH-3 and Ti(η 5-C 5H 5) 2Cl 2. The X-ray crystal structure of Ti(η 5-C 5H 5) 2(OPh) 2 has been determined and reveals a pseudo-tetrahedral arrangement of the two η 5-cyclopentadienyl and two phenoxide ligands around titanium. The Ti—O(Ph) distances are 1.907(3) Å and O—Ti—O is 98.1(2)°. The anti-tumour activities of Ti(η 5-C 5H 5)Cl(OC 6H 4NH 2-3) 2, Ti(η 5-C 5H 5)Cl(O 2CPh) 2 and Ti(η 5-C 5H 5) 2(O 2C(S)C 6H 4-1,2) have been assessed in vitro using a panel of seven human tumour cell lines.