Cyclopentadienyl ruthenium sulfide carbonyls and thiophene activation by iron and rhodium

The desulfurization and reduction of the sulfur-containing organic compounds in petroleum products is the objective of catalytic hydrodesulfurization (HDS), one of the largest applications of transition-metal catalysis. However, the specific mechanism for the process is not well understood. This thesis addresses certain aspects of HDS research from an organometallic perspective.A proposed intermediate during thiophene decomposition features thiophene $\sigma$-bound through an $\alpha$-carbon to a surface metal atom. Results from the reaction of ($\rm C\sb5H\sb5$)Fe(CO)(PPh$\sb3$)(2-C$\sb4$H$\sb3$S) and methyl triflate indicate the possible formation of two S-methylated configurational isomers. The first non-mercury containing bimetallic $\mu$-thienyl compound, ((C$\sb5$H$\sb5$)Fe(CO)$\sb2$) $\sb2$(2,5-C$\sb4$H$\sb2$S) was structurally characterized.The reaction of thiophenic compounds with Fe$\sb3$(CO)$\sb{12}$ resulted in metal insertion into the C-S bond. The known benzothiaferrole $\rm Fe\sb2(C\sb8H\sb6S)(CO)\sb6$ (1) was hydrogenated to give an insoluble iron-containing solid and a series of ethylbenzene derivatives. Oxidizing agents convert 1 to the carbonylated heterocycle thiocoumarin. $\rm Fe\sb2$(2-MeC$\sb4$H$\sb3$S)(CO)$\sb6$ desulfurizes to give the corresponding ferrole complex when heated.$\rm \lbrack (C\sb5 Me\sb5)Rh(TMT)\rbrack\sp{2+}$ (TMT = tetramethylthiophene) reacts with cobaltocene to give the new compound ($\rm C\sb5Me\sb5)Rh(\eta\sp4$-TMT), 2. The $\eta\sp4$-TMT ligand in 2 desulfurizes upon reaction with Fe$\sb3$(CO)$\sb{12}$ to give ($\rm C\sb5Me\sb5)Rh(C\sb4Me\sb4)Fe(CO)\sb3$. An x-ray diffraction study confirms that the Fe(CO)$\sb3$ fragment is included in the $\rm C\sb4Me\sb4$ ring. The thermolysis of 2 resulted in the formation of an ionic compound. The structurally characterized cation consists of four ($\rm C\sb5Me\sb5)Rh(\eta\sp4$-TMT) "units" bound to a central rhodium atom in a square planar fashion creating a "pinwheel" structure. A new mechanism for thiophene HDS was proposed.(($\rm C\sb5Me\sb4Et)Ru$) $\sb2$S$\sb6$(CO)$\sb2$ eliminates SCO to give (($\rm C\sb5Me\sb4Et)Ru$) $\sb2$S$\sb5$(CO). (($\rm C\sb5Me\sb4Et)Ru$) $\sb2$S$\sb4$ reacts with CO to form (($\rm C\sb5Me\sb4Et)Ru$) $\sb2$S$\sb4$(CO) (3). This is the first example of a metal-centered ligand addition to a cyclopentadienyl metal sulfide. The x-ray structure of 3 shows a $\rm Ru\sb2S\sb4$ core in a chair conformation with the bridging ($\eta\sp1$-S$\sb2$) ligands in a trans configuration. In the presence of phosphines, (($\rm C\sb5Me\sb4Et)Ru$) $\sb2$S$\sb4$ reacts with CO to form (($\rm C\sb5Me\sb4Et)Ru$) $\sb2$S$\sb2$(CO)$\sb2$.U of I OnlyETDs are only available to UIUC Users without author permissio