Titanocene pentasulfide is the

organotitanium compound Organotitanium chemistry is the science of organotitanium compounds describing their physical properties, synthesis, and reactions. Organotitanium compounds in organometallic chemistry contain carbon-titanium chemical bonds. They are reagents in o ...

with the formula (C₅H₅)₂TiS₅, commonly abbreviated as Cp₂TiS₅. This

metallocene A metallocene is a compound typically consisting of two cyclopentadienyl anions (, abbreviated Cp) bound to a metallic element, metal center (M) in the oxidation state II, with the resulting general formula Closely related to the metallocenes are ...

exists as a bright red solid that is soluble in organic solvents. It is of academic interest as a precursor to unusual allotropes of elemental sulfur as well as some related inorganic rings.

Preparation and structure

Titanocene pentasulfide is prepared by treating Cp₂TiCl₂ with polysulfide salts: It was first produced by the addition of elemental sulfur to

titanocene dicarbonyl Dicarbonylbis(cyclopentadienyl)titanium is the chemical compound with the formula (''η''5-C5H5)2Ti(CO)2, abbreviated Cp2Ti(CO)2. This maroon-coloured, air-sensitive species is soluble in aliphatic and aromatic solvents. It has been used for the ...

: :(C₅H₅)₂Ti(CO)₂ + S₈ → (C₅H₅)₂TiS₅ + 2 CO The complex is viewed as a pseudotetrahedral complex of Ti(IV). The Ti–S distances are 2.420 and 2.446 Å and the S–S bond distances are of a normal range, 2.051–2.059 Å. The molecule exhibits a dynamic NMR spectrum owing to the chair–chair equilibrium of the TiS₅ ring which equivalizes the Cp signals at high temperatures.

Reactions

Cp₂TiS₅ reacts with sulfur and selenium chlorides, E_''x''Cl₂, to afford titanocene dichloride and various S_5+''x'' and S₅Se_''x'' rings. Illustrative is the synthesis of S₇ from

disulfur dichloride Disulfur dichloride is the inorganic compound of sulfur and chlorine with the Chemical formula, formula S2Cl2. Some alternative names for this compound are ''sulfur monochloride'' (the name implied by its empirical formula, SCl), ''disulphur dich ...

: :(C₅H₅)₂TiS₅ + S₂Cl₂ → (C₅H₅)₂TiCl₂ + S₇ It also reacts with

alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

s and

ketene In organic chemistry, a ketene is an organic compound of the form , where R and R' are two arbitrary monovalent chemical groups (or two separate substitution sites in the same molecule). The name may also refer to the specific compound etheno ...

s to give heterocycles composed of Ti, C and S. With trialkylphosphines, the cycle

dimerize A dimer () ('' di-'', "two" + ''-mer'', "parts") is an oligomer consisting of two monomers joined by bonds that can be either strong or weak, covalent or intermolecular. Dimers also have significant implications in polymer chemistry, inorganic ch ...

into rings of various sizes, depending on the trialkylphosphine used. Selected reactions of titanocene pentasulfide

References

{{Titanium compounds Sulfides Titanocenes Titanium(IV) compounds