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|Title:||Transition Metal Complexes With Hydrosulfido and Thiophene Ligands|
|Author(s):||Ruffing, Charles Joseph|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The removal of thiophenes and dibenzothiophenes from petroleum by catalytic hydrodesulfurization is becoming increasingly important to fossil fuel processing. The reaction mechanism of this process is proposed to involve thiophene coordination to the metal surface and subsequent hydrogen transfer from a surface hydrosulfido group to the bound substate. Transitional metal complexes with SH or thiophene ligands may be thought of as molecular analogs of these proposed surface species.
The reactivity of the metallothiols Cp(,2)M(SH)(,2) (M = Ti,W) was found to differ depending on the metal center. While the titanium compound was relatively unreactive, the tungsten complex was readily alkylated with methyl iodide. Cp(,2)W(SH)(,2) was also found to react with an isonitrile ligand in the complex Pd(CH(,3)NC)(,2)dppe (PF(,6))(,2) to afford the dithiocarbamate complex Cp(,2)WS(,2)CN(H)CH(,3) (PF(,6)). This reaction does not occur with uncoordinated methyl isonitrile. The compound Cp(,2)Ti(SH)(,2) was found to function as a bidentate donor to molybdenum tetracarbonyl to form the bimetallic species Cp(,2)Ti(SH)(,2)Mo(CO)(,4). The inversion of the bridging ligands was investigated by DNMR spectroscopy. The reactivity of the dimeric molecule was found to be greater than the monomeric titanium precursor, as evidenced by the ease of alkylation at sulfur.
In order to induce thiophene coordination to a metal center, the potentially chelating ligands 2-thienyl methylcyclopentadiene and di-tolylphosphinodibenzothiophene were prepared and characterized. The substitued cyclopentadiene ligand was found to interact with the ruthenium atom in (ThCp)Ru(PPh(,3))(,2) (BF(,4)), as determined by the spectroscopy of the cationic complex. The ruthenium complex of di-tolylphosphinodibenzothiophene was formulated as RuCl(,2)(tol(,2)PDBT)(,2) and its structure determined by x-ray crystallography. This is the first example of a thiophene molecule coordinating through sulfur to a metal.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985.
|Date Available in IDEALS:||2014-12-15|