Development of nickel thiolates as templates for sulfoxide synthesis /
The cis-dithiolate complex [1,5-bis(2-mercapto-2methylpropyl)-1,5-diazacyclooctane]Ni(II), (bme*-daco)Ni and the statically less-hindered analogue, (bme-daco)Ni react at sulfur with a wide variety of electroplates such as organic halides, oxygen-atom sources and metal ions. Density functional calcul...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1999.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=730316761&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The cis-dithiolate complex [1,5-bis(2-mercapto-2methylpropyl)-1,5-diazacyclooctane]Ni(II), (bme*-daco)Ni and the statically less-hindered analogue, (bme-daco)Ni react at sulfur with a wide variety of electroplates such as organic halides, oxygen-atom sources and metal ions. Density functional calculations for (bme-daco)Ni, (bme*-daco)Ni and S-methylated derivatives were performed to delineate the frontier molecular orbitals. The presence of the a-carbon methyl groups creates steric bulk about the thiolate, but no significant differences in molecular orbitals were found. The relative-nucleophilicities of (bme-daco)Ni, (bme*-daco)Ni and derivatives were studied by determining the rate constants for the thiolate-sulfur alkylation of these complexes. Electrochemical data was used to gauge the electron density at nickel as a function of the sulfur donor. As the density functional calculations have shown, the ¹³-C methyl groups do not contribute significantly to the electron-richness of the sulfur. The differences in the rates of alkylation can be attributed to the nature of the electrophile and the steric encumbrance about the thiolate sulfurs. Alkylation of the monosulfoxide, Ni-4*, with MeI and Me₃OBF₄ resulted in O-atom transfer and rearrangement. Products of the reaction were a mixed sulfenato/thioether complex and a sulfinato/thioether complex. The relative distributions of these complexes were dependent upon the alkylating agent used. The sulfenato/thioether complex was favored when MeI is employed, while the opposite was role for Me₃OBF₄. The formulation of the sulfenato/thioether complex was based on mass spectrometry data and alkylation data using ¹³C-labeled MeI. N-methyl-diazacycloheptane or Medach was used to develop a new N₂S ligand capable of generating a monomeric nickel complex. Alkylation with alkyl halides resulted in thioether formation and halide exchange at the nickel. Cyanide demonstrated its ability to displace the chloride as well. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xv, 135 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 113-119). |