Title page for ETD etd-09292009-020335


Type of Document Master's Thesis
Author Grieb, Arthur L.
URN etd-09292009-020335
Title Synthesis and characterization of Ir(III) metallacycles derived from thiophene and related compounds :models for the hydrodesulfurization process
Degree Master of Science
Department Chemistry
Advisory Committee
Advisor Name Title
Merola, Joseph S. Committee Chair
Anderson, Mark R. Committee Member
Hanson, Brian E. Committee Member
Keywords
  • Thiophenes
Date of Defense 1993-08-05
Availability restricted
Abstract

Researchers use metal-thiophene complexes to mimic reactions which occur inside hydrodesulfurization (HDS) reactors. Information obtained from these model studies may often be applied to understanding the mechanisms involved with commercially used catalysts. Certain mechanisms1 for HDS propose thiophene ring cleavage,forming a metallacycle, prior to hydrogenation of one double bond. There are, however, limited examples of complexes derived from C-S cleavage.2,3,4

Thermal reactions of the iridium complex, [Ir(COD)(PMe3)3]Cl (COD=1,5- cyclooctadiene), with thiophene, thiazole, 4-methyl thiazole and 5-methyl thiazole yields the C-S addition metallacycles (Me3P)3Ir-(CH=CHCH=S)CI (I), \ (Me3P)3Ir-(CH=NCH=CHS)CI (II), (Me3P)3Ir-CCH=NC(CH3)=CHS)CI (III) and (Me3P)3Ir (CH=NCH=C(CH3)S)CI (IV), respectively. These compounds were characterized using the following methods: 1 H NMR, 13C NMR, 31 P NMR, elemental analysis and single crystal x-ray diffraction.

Following C-S addition to [Ir(COD)(PMe3)3]CI, nitrogen present in the thiazoles exhibit enhanced nucleophilicity. For exmnple, compounds II-IV react with methylene chloride to form dimers: CH2[NCR=CR'SIr(Cl)(PMe3)3CH]2. The above compounds are soluble in water and react with PF6 salts liberating the chloride atom from the Ir center. pKb measurements were recorded as well.

This thesis describes the synthesis and examination of con1pounds I-IV as they may model the HDS process. Compounds II-IV represent the first examples of ring opened thiazole metallacycles with iridium.

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