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Title:Synthesis and Reactivity of Some Organometallic Chalcogenide Complexes
Author(s):Giolando, Dean Mark
Department / Program:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Chemistry, Inorganic
Abstract:Titanocene pentasulfide (1) is rapidly desulfurized by tertiary phosphines to give 1,4-(Cp$\sb2$Ti) $\sb2$S$\sb4$ (2) and 1,5-(Cp$\sb2$Ti) $\sb2$S$\sb6$ (3) (Cp = $\eta\sp5$-C$\sb5$H$\sb5$). The Ti$\sb2$S$\sb4$/Ti$\sb2$S$\sb6$ product distribution arises from the competition between coupling of two (RC$\sb5$H$\sb4$)$\sb2$TiS$\sb3$ units and further desulfurization of (RC$\sb5$H$\sb4$)$\sb2$TiS$\sb3$ by PR$\sb3$. The synthesis of 1,4-(Cp$\sb2$Ti) $\sb2$S$\sb4$ from an intermediate perthiocarbonato compound, Cp$\sb2$TiCS$\sb4$, may also involve an unstable Cp$\sb2$TiS$\sb2$ species. The same is probably also true for the oxidation of Cp$\sb2$Ti(SH)$\sb2$.
In the presence of unhindered ketones 1 reacts with sulfide anion, S$\sp{2-}$, to give 1,4-Cp$\sb2$TiS$\sb4$CR$\sb2$ heterocycles. Both the 1,3- and 1,4-Cp$\sb2$TiS$\sb4$CH$\sb2$ isomers are produced when CH$\sb2$Br$\sb2$ is used in place of the ketones. The substitution of a sulfur atom by a CR$\sb2$ unit in the cyclo-TiS$\sb5$ moiety is proposed to involve heterolytic cleavage of the TiS$\sb5$ ring by an anionic sulfur nucleophile.
Dithiolene synthesis from the Cp$\sb2$Ti-S$\sb{\rm X}$ compounds occur via the intermediacy of a vinyldisulfide compound, Cp$\sb2$TiSC$\sb2$(CO$\sb2$CH$\sb3$)$\sb2$S (4). Subsequent intramolecular rearrangement to affords the dithiolene. The reason that the vinyldisulfide had not previously been identified in the pentasulfide chemistry is attributable to the high activation energy associated with the addition of DMAD to the poorly nucleophilic (RC$\sb5$H$\sb4$)$\sb2$TiS$\sb5$.
The synthesis and characterization of tellurium analogs (ditellurene) of dithiolenes was also explored. The first examples of ditellurene complexe were obtained with PtCl$\sb2$(P(C$\sb6$H$\sb5$)$\sb3$)$\sb2$. The ligands o-C$\sb6$H$\sb4$(TeLi)$\sb2$ and 1,2-C$\sb5$H$\sb6$(TeLi)$\sb2$ were prepared, and found to react readily with PtCl$\sb2$(P(C$\sb6$H$\sb5$)$\sb3$)$\sb2$ to provide PtTe$\sb2$C$\sb6$H$\sb4$(P(C$\sb6$H$\sb5$)$\sb3$)$\sb2$ (5) and PtTe$\sb2$C$\sb6$H$\sb4$(P(C$\sb6$H$\sb5$)$\sb3$)$\sb2$ (6), respectively. Also, o-C$\sb6$H$\sb4$(SLi)Li can be used to prepare PtTeSC$\sb6$H$\sb4$(P(C$\sb6$H$\sb5$)$\sb3$)$\sb2$ (7) and PtSeSC$\sb6$H$\sb4$(P(C$\sb6$H$\sb5$)$\sb3$)$\sb2$.
Examples of Sila-1,1-dithiolate complexes, Cp$\sb2$MS$\sb2$SiMe$\sb2$ (M = Ti (8) and V) and PtS$\sb2$SiMe$\sb2$(P(C$\sb6$H$\sb5$)$\sb3$)$\sb2$, were prepared by treating (Me$\sb2$SiS)$\sb3$/Li$\sb2$S with the metal dichlorides. Compound 8 is particularly interesting because it contains two potentially reactive sites; Ti-S and Si-S bonds. The reaction of 8 with transition metal (or main group) dichlorides affords Cp$\sb2$TiCl$\sb2$ ($>$90%) without the formation of Me$\sb2$SiCl$\sb2$. Indicating that reaction at titanium is preferred. The reactivity of Cp$\sb2$TiS$\sb2$SiMe$\sb2$ with oxometallates gave sulfiding reactions, without reduction occurring. Compound 8 converts WO$\sb{\rm x}$S$\sb{\rm 4-x}\sp{2-}$ (X = 4, 3, 2) and TaW$\sb5$O$\sb \sp{3-}$ into WS$\sb4\sp{2-}$ and TaW$\sb5$O$\sb $S$\sp{3-}$, respectively.
Issue Date:1987
Description:233 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1987.
Other Identifier(s):(UMI)AAI8721640
Date Available in IDEALS:2014-12-15
Date Deposited:1987

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