Titanocene pentasulfide is theorganotitanium compound with the formula (C5H5)2TiS5, commonly abbreviated as Cp2TiS5. Thismetallocene exists as a bright red solid that is soluble in organic solvents. It is of academic interest as a precursor to unusualallotropes of elemental sulfur as well as some related inorganic rings.
Titanocene pentasulfide is prepared by treatingCp2TiCl2 with polysulfide salts:[1] It was first produced by the addition of elemental sulfur totitanocene 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 adynamic NMR spectrum owing to the chair–chair equilibrium of the TiS5 ring which equivalizes the Cp signals at high temperatures.[4]
Cp2TiS5 reacts with sulfur and selenium chlorides, ExCl2, to afford titanocene dichloride and various S5+x and S5Sex rings. Illustrative is the synthesis of S7 fromdisulfur dichloride:[5]
(C5H5)2TiS5 + S2Cl2 → (C5H5)2TiCl2 + S7
It also reacts withalkenes andketenes to give heterocycles composed of Ti, C and S. Withtrialkylphosphines, the cycledimerize into rings of various sizes, depending on the trialkylphosphine used.[6]
^Shaver, Alan; McCall, James M.; Marmolejo, Gabriela (1990). "Cyclometallapolysulfanes (And Selanes) of Bis(η5 -Cyclopentadienyl) Titanium(IV), Zirconium(IV), Molybdenum(IV), and Tungsten(IV)".Inorganic Syntheses.Inorg. Synth. Vol. 27. pp. 59–65.doi:10.1002/9780470132586.ch11.ISBN978-0-470-13258-6.
^"π-Complexes of Group IVA metals with cyclopentadiene, indene, and fluorine".Bull. Soc. Chim. France.11:3548–64. 1966.
^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 (7):410–411.doi:10.1039/C29700000410.
^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 (12):1823–1829.doi:10.1021/om00090a008.
^Steudel, Ralf; Eckert, Bodo (2003). "Solid Sulfur Allotropes Sulfur Allotropes".Topics in Current Chemistry.230:1–80.doi:10.1007/b12110.
^Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999).Advanced Inorganic Chemistry (6th ed.). Wiley.ISBN978-0-471-19957-1.
