The pentachalcogenides (C5H4R)2TiE5 (R = H, CH3; E = S, Se) react with acetylenes ZC=CZ (Z = CO2CH3, CF3) to give the alkene dichalcogenide compounds, (C5H4R)2TiE2C2Z 2, which were isolated as dark green crystalline solids. The dithiolene syntheses proceed in ca. 40% yield at 140 °C while the corresponding diselenene synthesis was quantitative at 80 °C. The new compounds were characterized by 1H, 13C, 19F, and 77Se NMR, IR, mass spectrometry, and electrochemistry. (C5H4CH3)2TiS2C 2(CO2CH3)2 crystallizes in the triclinic space group P1-Cl1 (No. 2) with one molecule per unit cell of dimensions a = 9.312 (2) Å, b = 9.886 (2) Å, c = 11.225 (3) Å, α= 109.35 (2)°, β = 88.25 (2)°, and γ = 105.78 (2)°. Empirically weighted full-matrix least-squares refinement employing isotropic thermal parameters for hydrogen atoms and anisotropic thermal parameters for all others converged to R1(based on f) = 0.032 and R2 = 0.039 for 4098 independent reflections having 2θMoKα ≤ 58.7° and I > 3σ(I). The structure analysis revealed a conventional bis(methylcyclopentadienyl)titanium moiety chelated by the sulfur atoms of the dithiolene. The conversion of (C5H5)2TiSe5 to its alkene diselenide derivative was characterized as a function of reactant concentrations and temperature. In refluxing 1,2-dichloroethane solution, this reaction was found to be first order with respect to both acetylene and pentaselenide concentrations, the second-order rate constant being 1.58 × 10-3 M-1 s-1 at 83.5 °C. The compounds (C5H4R)2TiE2C2Z 2 were found to react with a variety of dichloro compounds, LnMCl2, to give the ligand-exchange products LnME2C2Z2 (Z = CO2CH3) and (C5H4R)2TiCl2. In this way the following new compounds were prepared: Ni(Se2C2Z2)(Ph2PCH 2CH2CH2PPh2), Pt-(E2C2Z2)(PPh3)2 (E = S, Se), Pt2(Se2C2Z2)2(Ph 2PC2PPh2)2, (AsPh4)[Rh(Se2C2Z2)(CO) 2], and SCSe2C2Z2. Alcoholysis of (C5H5)2TiSe2C2(CO 2CH3)2 in basic methanol gave solutions of Na2Se2C2(CO2CH3) 2, which was derivatized with CH3I (2 equiv) and cis-PtCl2(PPh3)2.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry