5072-91-3Relevant academic research and scientific papers
Thiolato ligand transfer from bis(thiolato)titanocenes to platinum(II) complexes
Osakada, Kohtaro,Kawaguchi, Yasuharu,Yamamoto, Takakazu
, p. 4542 - 4548 (1995)
Reactions of Cp2Ti(SEt)2 (1a) and Cp2Ti(S-i-Pr)2 (1b) with equimolar PtCl2(cod)2 give bis-(thiolato)platinum complexes, [Pt(SEt)2]n (2a) and [Pt(S-i-Pr)2]n (2b), respectively, accompanied by formation of Cp2TiCl2. Complexes 2a,b, which are insoluble in common organic solvents, are characterized by elemental analyses and by CP-MAS 13C NMR spectra in the solid state. Cp2Ti(SC6H4-p-Me)2 (1c), Cp2Ti(SPh)2 (1d), Cp2Ti(S2C6H4) (1e), and Cp2Ti(S2C2H4) (1f) react with equimolar PtCl2(cod) smoothly to give mixtures of Cp2TiCl2 and (thiolato)-platinum complexes with the cod ligand, Pt(SC6H4-p-Me)2(cod) (3c), Pt(SPh)2(cod) (3d), Pt-(S2C6H4)(cod) (3e), and Pt(S2C2H4)(cod) (3f), respectively. Reactions of 1a with excess PtCl2(cod) in THF and in CH2Cl2 cause a color change of the solution indicating initial formation of Cp2TiCl(SEt) followed by its further reaction with Pt complexes to give Cp2-TiCl2. The latter step, which is much slower than the former, obeys pseudo-first-order kinetics with respect to [Cp2TiCl(SEt)]. The observed rate constants, kobsd, of the reaction in CH2Cl2 are proportional to [PtCl2(cod)]. Temperature dependence of the rate constants in THF gives the kinetic parameters Ea = 57.4 kJ mol-1, ΔH? = 54.8 kJ mol-1, ΔS? = -106 J mol-1 K-1, and ΔG? = 86.3 kJ mol-1 at 298 K. Reaction of 1b with excess PtCl2(cod) also gives Cp2TiCl2 through Cp2TiCl(S-i-Pr). The kinetic parameters of the reaction are Ea = 62.3 kJ mol-1, ΔH? = 59.8 kJ mol-1, ΔS? = -124 J mol-1 K-1, and ΔG? = 96.7 kJ mol-1 at 298 K. The absorption spectrum of a reaction mixture of 1f with excess PtCl2(cod) shows a decrease in the peak due to 1f with concomitant growth of a peak due to Cp2TiCl2. The reaction obeys 0.5th-order kinetics with respect to [1f]. Reactions of 1c,d with equimolar PtCl2(cod) in toluene give the complexes formulated as [Cp2Ti(SAr)2PtCl2(cod)] (4c, Ar = C6H4-P-Me; 4d, Ar = Ph), which are characterized by elemental analyses and 13C NMR spectra in the solid state. Dissolution of 4c,d in THF causes formation of a mixture of Cp2-TiCl2 with 3c,d, respectively.
