Kinetic results and reaction pathways of intermolecular thiolato ligand migration between titanocene complexes and from Cp2TiX(SAr) (X = Cl, SAr) to PtCl(Me)(cod) (cod = eta(2),eta(2)-1,5-cyclooctadiene)

Cp2TiCl(SPh) (la), prepared from an equimolar reaction of Cp2TiCl2 with NaS Ph, undergoes partial and reversible disproportionation in THF into Cp2TiCl 2 and Cp2Ti(SPh)(2) (2a). The thermodynamic parameters of the reaction are determined to be Delta H degrees = 13.0(0.6) kJ mol(-1) and Delta S degrees = 14(2) J K-1 mol(-1) at 298 K. An equimolar reaction of Cp2Ti-(SAr)(2) (2 a: Ar = C6H5, 2b: Ar = C6H4Me-p, 2c: Ar = C6H4OMe-p, 2d: Ar = C6H4Cl-p, 2e: Ar = C10H7) with PtCl(Me)(cod) in THF leads to an intermolecular exchange of the thiolato and chloro ligands to afford Pt(Me)(SAr)(cod) (3a: Ar = C6H 5, 3b: Ar = C6H4Me-p, 3c: Ar = C6H4OMe-p, 3d: Ar = C6H4Cl-p, 3e: Ar = C10H7 ) Ti complexes: Cp2TiCl2, Cp2TiCl(SAr), Cp2Ti(SAr)(2), and a minor amount o f (Cp2TiCl)(2)O, are also present in the products. Absorption spectra of a solution of 2a and excess PtCl(Me)(cod) exhibit distinct changes due to the thiolato ligand transfer, and indicate initial formation of la and its sub sequent reaction with the Pt complex to form Cp2TiCl2. The reaction of la w ith excess PtCl(Me)(cod) obeys second-order kinetics to [1a]. The observed rate constants, k(obsd), increase with an increase in the concentration of PtCl(Me)(cod). Linear plots of the reciprocal of k(obsd) versus [1a](0)/[Pt Cl(Me)(cod)](0) are consistent with the reaction pathway involving the disp roportionation of la into an equimolar mixture of Cp2TiCl2 and 2a, the latt er of which readily reacts with PtCl(Me)(cod) to regenerate 1a.