| dc.contributor |
David A. Shultz, Committee Member |
|
| dc.contributor |
James D. Martin, Committee Member |
|
| dc.contributor |
Edmond F. Bowden, Committee Member |
|
| dc.contributor |
T. Brent Gunnoe, Committee Chair |
|
| dc.creator |
Pittard, Karl A. |
|
| dc.date |
2010-04-02T18:57:59Z |
|
| dc.date |
2010-04-02T18:57:59Z |
|
| dc.date |
2007-05-01 |
|
| dc.date.accessioned |
2023-02-28T17:08:27Z |
|
| dc.date.available |
2023-02-28T17:08:27Z |
|
| dc.identifier |
etd-04172007-141732 |
|
| dc.identifier |
http://www.lib.ncsu.edu/resolver/1840.16/4638 |
|
| dc.identifier.uri |
http://localhost:8080/xmlui/handle/CUHPOERS/265687 |
|
| dc.description |
The RuII complex TpRu(CO)(NCMe)Me (Tp = hydridotris(pyrazolyl)borate) initiates carbon-hydrogen bond activation at the 2-position of furan and thiophene to produce methane and TpRu(CO)(NCMe)Ar (Ar = 2-furyl or 2-thienyl). Solid-state structures have been determined for TpRu(CO)(NCMe)(2-thienyl) and [TpRu(CO)(-C,S-thienyl)]2. The complex TpRu(CO)(NCMe)(2-furyl) serves as a catalyst for the formation of 2-ethylfuran from ethylene and furan. Similar catalytic reactivity was observed with TpRu(CO)(NCMe)(2-thienyl) for the production of 2-ethylthiophene. Density functional theory (DFT) calculations of the C-H activation of furan by {(TAB)Ru(CO)Me} (TAB = tris(azo)borate) indicate that the C-H activation sequence does not proceed through a RuIV oxidative addition intermediate.
The reaction of TpRu(CO)(NCMe)Me and pyrrole forms TpRu(CO){ 2-N,N-(H)N=C(Me)(NC4H3)}. The formation of complex TpRu(CO){2-N,N-(H)N=C(Me)(NC4H3)} involves the cleavage of the N-H bond and 2-position C-H bond of pyrrole as well as a C-C bond forming step between pyrrole and the acetonitrile ligand of {TpRu(CO)(NCMe)}. Mechanistic studies indicate that the most likely reaction pathway involves initial metal-mediated N-H activation of pyrrole to produce TpRu(CO)(NCMe)(N-pyrrolyl) followed by C-C bond formation and proton transfer. Complex TpRu(CO)(NCMe)(N-pyrrolyl) has been independently prepared. At elevated temperatures, TpRu(CO)(NCMe)(N-pyrrolyl) converts to TpRu(CO){2-N,N-(H)N=C(Me)(NC4H3)}. Single crystal X-ray analysis has been achieved for TpRu(CO)(NCMe)(N-pyrrolyl), [TpRu(CO)(NCMe)(1-O-OC4H8) and TpRu(CO){2-N,N-(H)N=C(Me)(NC4H3)}. Computational studies support the suggested selectivity for initial N-H bond cleavage in preference to C-H bond activation.
Rational design for a more electron-poor hydroarylation catalyst was discussed. Synthesis of Mp (Mp = tris(pyrazolyl)methane) complexes of the type [MpRu(PPh3)(CO)H]BAr'4, [MpRu(PPh3)(CO)Cl]BAr'4, [MpRu(PPh3)(PMe3)Cl]Cl, [MpRu(PPh3)(PMe3)Cl]BAr'4, [MpRu(PPh3)2Cl]BAr'4, [MpRu(PPh3){P(OMe)3}Cl]Cl, [MpRu(PPh3)(NCMe)Cl]BAr'4, [MpRu(PPh3)(NCMe)Cl]BAr'4 and [MpRu(PPh3)(CO)Cl]BAr'4 accomplished. A single-crystal X-ray diffraction study was carried out on the complex [MpRu(PPh3)(PMe3)Cl]Cl. [MpRu(PPh3)2Me]BAr'4 was prepared and examined by Cyclic Voltammetry (CV) where the E1/2 = 1.19 V. C-H activation was observed when [MpRu(PPh3)2Me]BAr'4 was heated in neat C6D6. Orthometalation appears to dominate reactivity via intramolecular C-H activation of a PPh3 ligand, however CH3D was produced at elevated temperatures. A series of Ep (Ep = tris(pyrazolyl)ethane) complexes of the type MpRu(Cl)2PR3 (R = Ph, OMe, or Me) were also synthesized. The [EpRu(PPh3)(NCMe)(Cl)]Cl and [EpRu(PPh3)(PMe3)(Cl)]Cl complexes were observed spectroscopically as intermediates in these syntheses. Improved synthesis of [MpRu(PPh3)2Cl]Cl was also accomplished by improving the yield by 23%, over the previously reported yield of 53%. |
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| dc.rights |
I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis
sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee.
I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I
retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
|
| dc.subject |
heteroaromatic compounds |
|
| dc.subject |
C-H Activation |
|
| dc.title |
Activation of Carbon-Hydrogen Bonds Mediated by Ru(II) Complexes |
|