Structure, electrochemical and dynamic behavior of bis(pentamethylcyclopentadienyl)titanium(IV)dithiolene complexes

(eta(5)-C(5)Me(5))(2)Ti(dithiolene) complexes are prepared by reacting (eta(5)-C(5)Me(5))(2)TiCl2 with the dithiolene ligands dmit(2-) (1,3-dithiole-2-thione-4,5-dithiolate) or dddt(2-) (5,6-dihydro-1,4-dithiine-2,3-dithiolate). One reversible reduction wave and irreversible oxidation waves are observed by cyclic voltammetry for each complex at low scan rates. In (eta(5)-C(5)Me(5))(2)Ti(dddt), the first oxidation system becomes reversible at higher scan rates. (eta(5)-C(5)Me(5))(2)Ti(dmit) crystallizes in the orthorhombic system, space group Pca2(1) with a = 26.683(6), b = 8.485(1), c = 22.272(6) Angstrom, Z = 8, with two independent molecules in the unit cell. The TiS2C2 plane is folded along the S-S axis by 38 and 38.3 degrees in each independent molecule, respectively, to be compared with a value of 47 degrees in (eta(5)-C5H5)(2)Ti(dmit). Extended Huckel calculations show that the steric constraints of the Cp* ligands prevail over the metal-dithiolene interactions for explaining the actual geometry of such (eta(5)C(5)Me(5))(2)Ti(dithiolene) complexes. The dynamics of fluxional processes involved in the dithiolene ligand folding have been investigated by variable-temperature H-1 NMR studies and compared with the data reported for analogous (eta(5)-C5H5)(2)Ti(dithiolene) complexes.