Thallium(I) derivatives of monocyclopentadienylbis(ethane-1,2-dithiolato)titanium, TlTi(eta(5)-C5HnMe5-n)(edt)(2) {1, n = 0; 2, n = 4; edt = 1,2-S2C2H4}, have been synthesised and isolated in yields of 81 and 45%, respectively, from reactions of the corresponding reagents, Ti(eta(5)-C5HnMe5-n)Cl-3 and thallium salts of the ethane-1,2-dithiol. Conformational changes of the chelating dithiolate ligands in compound 1 have been monitored by variable temperature H-1-NMR spectroscopy. The preparation of compounds of the type TiCp(SAr)(3) (Cp = eta(5)-C5H5) has been investigated and the crystal structure of TiCp(SC6H5)(3), 3, determined by X-ray diffraction; the compound adopts a three-legged piano stool coordination geometry with two parallel phenyl rings (interplanar angle 2.0(2)degrees) directed away from the cyclopentadienyltitanium unit with inter-ring C-C contacts in the range 3.52-3.62 Angstrom; the third phenyl ring is approximately orthogonal to the other two and lies over a cyclopentadienyl ring of a neighbouring molecule with an intermolecular C-C contact of 3.373(16) Angstrom. (C) 1999 Elsevier Science S.A. All rights reserved.