Oxygenation and subsequent alkylation of nickel-bound thiolates /
The nickel dithiolate [1,5-bis(2-mercaptoethyl)-l,5-diazacyclooctane]nickel(II) (Ni-1) and its sterically hindered analogue (Ni-1*) react with excited state oxygen, [IA 02], to yield a variety of stable, isolable nickel S-oxygenated products. The reactions are solvent and concentration dependent wit...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1998.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=732834131&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The nickel dithiolate [1,5-bis(2-mercaptoethyl)-l,5-diazacyclooctane]nickel(II) (Ni-1) and its sterically hindered analogue (Ni-1*) react with excited state oxygen, [IA 02], to yield a variety of stable, isolable nickel S-oxygenated products. The reactions are solvent and concentration dependent with metallosulfones generally favored in acetonitrile at low concentrations and metallosulfoxides generally favored in methanol at higher nickel concentrations. The ligand also directs the product distribution with Ni-l more often directs the product distribution with Ni-l more often Mechanisms are proposed that are consistent with the observed product distributions and comparisons to the much studied oxygenation of organic sulfides. Density functional theory calculations for Ni-l and its monosulfone and monosulfoxide derivatives were also performed. Analysis of the bissulfoxide, Ni-5*, synthesized from a mixture of [160 /180] by Positive Ion Electrospray Ionization Mass Spectrometry shows that [02] adds as a molecule across the cis-sulfur sites. Alkylation of the bissulfoxide, Ni-5*, With l,3-dibromopropane results in oxygen transfer and isolation of a sulfone/thioether complex, [Ni- 2*(CH2)3Br1Br]. The product has been characterized by a variety of techniques including elemental analysis, infrared spectroscopy, cyclice mass spectrometry, voltammeter and UV-visible spectroscopy. Attempts to crystallize the product resulted in isolation of a decomposition product, [(Ni-2*(CH93Ni-2*1NiBr4]. Alkylation of the monosulfoxide, Ni-4*, and the sulfone/sulfoxide, Ni-6*, with l,3-dibromopropane also resulted in oxygen transfer and isolation of [INi- 2*(CH2)3Br1Br] although the yields were lower than with Ni-5*. The new tridentate diazacycloheptane (Hmmp-dach), has been obtained by the stoichiometry reaction of l,4-diazacycloheptane and isobutylene sulfide. The ligand complexes nickel to yield a NZS ligand, [l-(2-methyl-2-mercaptoethylpropyl)-l ,4- dimeric, thiolate bridged cation with each nickel residing in a square planar N2S2 environment. Alkylation of the dimer with the protein modification eagent iodoacetamide results in coordination of the acetamide oxygen and cleavage of the dimer. The product can be isolated as dark blue crystals which have been identified as the octahedral nickel complex [(l-(4,4-dimethyl-3-thiapentanaide)-l,4- diazacytrloheptane)nickel) chloride iodide, [g(dtp- dach)Ni)(C1)(1)]. Reaction of [glmmp- dach)2Ni2jC12] with cyanide yields the presumably square planar organometallic nickel complex [(mmp-dachlNicN]. Addition of methyl iodide to solutions of the yellow product results in alkylation. Infrared spectroscopy product results in alkylation. Infrared spectroscopy thiolate S-alkylation rather than cyanide N- alkylation. |
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| Item Description: | Vita. |
| Physical Description: | xv, 154 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references: pages 110-117. |