Titanocene pentasulfide

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Titanocene pentasulfide
Pentasulfur-titanocene complex structure.png
Identifiers
CAS number 12116-82-4 YesY
Properties
Molecular formula C10H10S5Ti
Molar mass 338.382
Appearance red solid
Structure
Coordination
geometry
Dist. tetrahedral
Related compounds
Related compounds Zirconocene pentasulfide. titanocene dichloride
Except where noted otherwise, 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[edit]

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 A and the S-S bond distances are of a normal range, between 2.051 to 2.059 Å.[3] The molecule exhibits a dynamic NMR spectrum owing the chair-chair equilibrium of the TiS5 ring which equivalences the Cp signals at high temperatures.[4]

Reactions[edit]

Cp2TiS5 reacts with sulfur and selenium chorides, ExCl2, to afford titanocene dichloride and various S5+x and S5Sex 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[edit]

  1. ^ Alan Shaver, James M. Mccall, Gabriela Marmolejo, "Cyclometallapolysulfanes (and Selanes) of Bis(η5-Cyclopentadienyl) Titanium(IV), Zirconium(IV), Molybdenum(IV), and Tungsten(IV)" Inorganic Syntheses, 1990, Vol. 27, pp. 59–65. doi:10.1002/9780470132586.ch11
  2. ^ "pi-Complexes of Group IVA metals with cyclopentadiene, indene, and fluorine" Bulletin de la Societe Chimique de France 1966, vol. 11, pp. 3548-64.
  3. ^ E. F. Epstein, I. Bernal "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. ^ Alan Shaver, James M. McCall "Preparation and Variable-Temperature NMR Studies of the Metallacyclosulfanes Cp2MS5and (MeSCp),MS3, Where M = Ti, Zr, and Hf" Organometallics 1984, vol. 3, pp. 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. ^ F. Albert Cotton; Geoffrey Wilkinson; Carlos A. Murillo; Manfred Bochmann (1999). Advanced Inorganic Chemistry, 6th Edition. Wiley. ISBN 978-0471199571.