SYNTHESIS AND CHARACTERIZATION OF DERIVATIVES OF LOPENTADIENYLBIS(ARENE-1,2-DITHIOLATO)TITANIUM(IV) - CRYSTAL-STRUCTURES OF M[TI(ETA(5)-C5ME5)(1,2-S2C6H4)(2)] [M = TL OR N(PPH3)(2)]

Thallium(I) derivatives of cyclopentadienylbis(arene-1,2-dithiolato)ti tanium, T1[Ti(eta(5)-C5HnMe5-n)-(S2C6H3R)(2) (1-6; n = 0, 4 or 5; R = H or Me), have been synthesised and isolated in yields of 31-65% from reactions of the corresponding trichloromonocyclopentadienyltitanium r eagents, Ti(eta(5)-C5HnMe5-n)Cl-3 and thallium salts of the benzene-1, 2-dithiol or toluene-3,4-dithiol in tetrahydrofuran. Reaction between T1[Ti(eta(5)-C5Me5)(1,2-S2C6H4)(2)] and bis(triphenylphosphine)iminium chloride, [N(PPh3)(3)]Cl, has also afforded the derivative [N(PPh3)(2 )][Ti(eta(5)-Me-5(5))(1,2-S2C6H4)(2)] 7. Products have been characteri sed by elemental analysis, NMR, IR and mass spectroscopy, and by X-ray diffraction. The structure of 7, in the crystalline state as a tris(d ichloromethane) solvate, comprises an ionic lattice containing discret e [Ti(eta(5)-C5Me5)(1,2-S2C6H4)(2)](-) anions of four-legged piano sto ol geometry with two chelating benzene-1,2-dithiolate ligands folded a long the S...S axis in exo and endo conformations, respectively, relat ive to the cyclopentadienyl ring. The crystal structure of T1[Ti(eta(5 )-C5Me5)(S2C6H4)(2)] 1 contains two forms of the anion [Ti(eta(5)-C5Me 5)(S2C6H4)(2)](-) in endolendo and endolexo conformations, respectivel y, which are unsymmetrically co-ordinated to the T1(I) cations. A T1(I ) ion is connected by two T1-S bonds to endo dithiolate ligands of eac h anion and there is also one T1-S interaction between pairs of endole ndo and endolexo forms. Additional weaker T1...S interactions to the T 1(I) ions generate a linked chain of dimeric units. In solution, NMR s pectra suggest a more symmetrical structure for all derivatives but sh ifts in resonances support the retention of co-ordinate links between the cyclopentadienylbis(arene-1,2-dithiolato)titanium anion and T1(I).