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The bioinorganic chemistry of N2S2 metal complexes: reactivity and ligating ability
dc.contributor.advisor | Darensbourg, Marcetta Y. | |
dc.creator | Golden, Melissa Lynn | |
dc.date.accessioned | 2005-08-29T14:35:25Z | |
dc.date.available | 2005-08-29T14:35:25Z | |
dc.date.created | 2002-05 | |
dc.date.issued | 2005-08-29 | |
dc.identifier.uri | https://hdl.handle.net/1969.1/2198 | |
dc.description.abstract | [N,N??-bis-(mercaptoethyl)-1,5-diazacyclooctanato]NiII, Ni-1, is known to undergo metallation reactions with numerous metals. [N,N??-bis-(mercaptoethyl)-1,5-diazacycloheptanato]NiII, (bme-dach)Ni or Ni-1??, differs from Ni-1 by one less carbon in its diazacycle backbone ring producing subtle differences in N2S2Ni geometry. Metallation of Ni-1?? with PdCl2, Pd(NO3)2, and NiBr2 produced three structural forms: Ni2Pd basket, Ni4Pd2 C4-paddlewheel, and Ni3 slant chair. In attempts to provide a rationale for the heterogeneity in the active site of Acetyl coA Synthase, metal ion capture studies of Ni-1 in methanol found a qualitative ranking of metal ion preference: Zn2+ < Ni2+ < Cu+. Formation constants for metal ion capture of Ni-1?? in water were determined for Pb2+, Ni2+, Zn2+, Cu+, and Ag+. A quantitative estimate places copper some 15 orders of magnitude above nickel or zinc in binding affinity. Sulfur dioxide uptake by Ni-1?? is characterized by significant color change, improved adduct solubility, and reversible binding of two equivalents of SO2. These combined properties establish Ni-1?? as a suitable model for gas uptake at nickel thiolate sites and as a possibly useful chemical sensor for this poisonous gas. Comparisons of molecular structures, ν(SO) stretching frequencies, and thermal gravimetric analyses are made to reported adducts including the diazacyclooctane derivative, Ni-1·2SO2. Visual SO2 detection limits of Ni-1 and Ni-1?? are established at 25 ppm and 100 ppm, respectively. Structural studies of products resulting from reaction at the nucleophilic S-sites of (bme-dach)Ni and [(bme-dach)Zn]2 included acetyl chloride and sodium iodoacetate as electrophiles are shown. The acetyl group is a natural electrophile important to the citric acid cycle. Acetylation of (bme-dach)Ni produces a five coordinate, paramagnetic species. Iodoacetate is a cysteine modification agent known to inhibit enzymatic activity. The reaction of (bme-dach)Ni and sodium iodoacetate yields a blue, six coordinate nickel complex in a N2S2O2 donor environment. The bismercaptodiazacycloheptane ligand binds lead(II) forming an unprecedented structural form of N2S2M dimers, in which Pb2+ is largely bound to sulfur in a highly distorted trigonal geometry. Its unusual structure is described in comparison to other derivatives of the bme-daco ligand. The synthesis and structural characterization of square pyramidal (bme-dach)GaCl are also given and compared to the analogous (bme-daco)GaCl. | en |
dc.format.extent | 4714977 bytes | en |
dc.format.medium | electronic | en |
dc.format.mimetype | application/pdf | |
dc.language.iso | en_US | |
dc.publisher | Texas A&M University | |
dc.subject | N2S2Ni | en |
dc.subject | metallothiolate | en |
dc.subject | sensors | en |
dc.subject | sulfur dioxide | en |
dc.subject | acetyl coA synthase | en |
dc.subject | CODH/ACS | en |
dc.title | The bioinorganic chemistry of N2S2 metal complexes: reactivity and ligating ability | en |
dc.type | Book | en |
dc.type | Thesis | en |
thesis.degree.department | Chemistry | en |
thesis.degree.discipline | Chemistry | en |
thesis.degree.grantor | Texas A&M University | en |
thesis.degree.name | Doctor of Philosophy | en |
thesis.degree.level | Doctoral | en |
dc.contributor.committeeMember | Lindahl, Paul A. | |
dc.contributor.committeeMember | Autenrieth, Robin L. | |
dc.contributor.committeeMember | Miller, Stephen A. | |
dc.type.genre | Electronic Dissertation | en |
dc.type.material | text | en |
dc.format.digitalOrigin | born digital | en |
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