Titanocene sulfide chemistry

Base-Promoted Reactions of Organostibines with Alkynes and Organic Halides to Give Chalcogenated (Z)-Olefins and Ethers

Herein, with air-stable chalcogenated stibines (Sb-ER) as organometallic chalcogenating reagents, we developed base-promoted (Z)-hydrochalcogenation of alkynes with DMSO/DMSO-d₆ as hydrogen/deuterium sources, giving chalcogenated (Z)-olefins in good yields and with excellent regioselectivity. These reagents, easily synthesized from halostibines with in situ generated [Zn(ER)₂] at room temperature within a few minutes, could be also used in the base-promoted C(sp³)-S(Se) cross-coupling with C(sp³)-X and copper-catalyzed C(sp²)-S(Se) cross-coupling with C(sp²)-X (X = F, CI, Br, I) under mild conditions. This protocol could also be simply extended to organobismuth complexes (Bi-ER) with good functional tolerance.

Titanocene Selenide Sulfides Revisited: Formation, Stabilities, and NMR Spectroscopic Properties

[TiCp₂S₅] (phase A), [TiCp₂Se₅] (phase F), and five solid solutions of mixed titanocene selenide sulfides [TiCp₂Se_xS_5−x] (Cp = C₅H₅⁻) with the initial Se:S ranging from 1:4 to 4:1 (phases B–E) were prepared by reduction of elemental sulfur or selenium or their mixtures by lithium triethylhydridoborate in thf followed by the treatment with titanocene dichloride [TiCp₂Cl₂]. Their ⁷⁷Se and ¹³C NMR spectra were recorded from the CS₂ solution. The definite assignment of the ⁷⁷Se NMR spectra was based on the PBE0/def2-TZVPP calculations of the ⁷⁷Se chemical shifts and is supported by ¹³C NMR spectra of the samples. The following complexes in varying ratios were identified in the CS₂ solutions of the phases B–E: [TiCp₂Se₅] (5₁), [TiCp₂Se₄S] (4₁), [TiCp₂Se₃S₂] (3₁), [TiCp₂SSe₃S] (3₆), [TiCp₂SSe₂S₂] (2₅), [TiCp₂SSeS₃] (1₂), and [TiCp₂S₅] (0₁). The disorder scheme in the chalcogen atom positions of the phases B–E observed upon crystal structure determinations is consistent with the spectral assignment. The enthalpies of formation calculated for all twenty [TiCp₂Se_xS_5−x] (x = 0–5) at DLPNO-CCSD(T)/CBS level including corrections for core-valence correlation and scalar relativistic, as well as spin-orbit coupling contributions indicated that within a given chemical composition, the isomers of most favourable enthalpy of formation were those, which were observed by ⁷⁷Se and ¹³C NMR spectroscopy.

Metalation Studies on Titanocene Dithiolates

Titanocene bis-arylthiolates [(C5H4X)(C5H4Y)Ti(SC6H4R)2] (X,Y = H, Cl; R = H, Me) can be prepared from the corresponding titanocene dichlorides by reacting with the thiols in the presence of DABCO as a base. They react with n-butyl lithium to give unstable Ti(III) radical anions. While the unsubstituted thiolates (X = Y = R = H) react with lithium Di-isopropylamide by decomposing to dimeric fulvalene-bridged and thiolate-bridged Ti(III) compounds, the ring-chlorinated compounds can be deprotonated with LDA and give appropriate electrophiles di-substituted and tri-substituted titanocene dithiolates.