Titanocene pentasulfide

Titanocene pentasulfide

Names
Other names titanocene pentasulfide
Identifiers
CAS Number	12116-82-4
Properties
Chemical formula	C10H10S5Ti
Molar mass	338.382
Appearance	red solid
Structure
Coordination geometry	Dist. tetrahedral
Related compounds
Related compounds	Zirconocene pentasulfide Titanocene dichloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Titanocene pentasulfide is the organotitanium compound with the formula (C₅H₅)₂TiS₅, commonly abbreviated as Cp₂TiS₅. This metallocene 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

Titanocene pentasulfide is prepared by treating Cp₂TiCl₂ with polysulfide salts:^[1] It was first produced by the addition of elemental sulfur to titanocene dicarbonyl:^[2]

(C₅H₅)₂Ti(CO)₂ +  ⁵⁄₈ 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.^[3] 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.^[4]

Reactions

Cp₂TiS₅ reacts with sulfur and selenium chlorides, E_xCl₂, to afford titanocene dichloride and various S_5+x and S₅Se_x rings. Illustrative is the synthesis of S₇ from disulfur dichloride:^[5]

(C₅H₅)₂TiS₅ + S₂Cl₂ → (C₅H₅)₂TiCl₂ + S₇

It also reacts with alkenes and ketenes to give heterocycles composed of Ti, C and S. With trialkylphosphines, the cycle dimerize into rings of various sizes, depending on the trialkylphosphine used.^[6]

Selected reactions of titanocene pentasulfide

References

1. Shaver, Alan; Mccall, James M.; Marmolejo, Gabriela (1990). "Cyclometallapolysulfanes (and Selanes) of Bis(η⁵-Cyclopentadienyl) Titanium(IV), Zirconium(IV), Molybdenum(IV), and Tungsten(IV)". Inorg.Synth. 27: 59–65. doi:10.1002/9780470132586.ch11.
2. "π-Complexes of Group IVA metals with cyclopentadiene, indene, and fluorine". Bull. Soc. Chim. France. 11: 3548–64. 1966.
3. Epstein, E. F.; Bernal, I. (1970). "Pentachalcogenide dianions in transition-metal complexes: crystal structure of bis-(π-cyclopentadienyl)titanium pentasulphide". J. Chem. Soc. D. 1970: 410–411. doi:10.1039/C29700000410.
4. Shaver, Alan; McCall, James M. (1984). "Preparation and Variable-Temperature NMR Studies of the Metallacyclosulfanes Cp₂MS₅ and (MeSCp)MS₃, Where M = Ti, Zr, and Hf". Organometallics. 3: 1823–1829.
5. Steudel, Ralf; Eckert, Bodo (2003). "Solid Sulfur Allotropes Sulfur Allotropes". Topics in Current Chemistry. 230: 1–80. doi:10.1007/b12110.
6. Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999). Advanced Inorganic Chemistry (6th ed.). Wiley. ISBN 978-0471199571.