Transition metal complexes of pendant arm derivatives of 1,5-diazacyclooctane /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1991.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | The synthesis of 1,5-diazacyclooctane.2HBr (DACO.2HBr) from hydrazine and 1,3-dibromopropane has been optimized and the isolation of the free base detailed. Reaction of the amine with ethylene oxide or ethylene sulfide produced the pendant hydroxyethyl (N2O2) and mercaptoethyl (N2S2) derivatives, respectively. All of the ligands were fully characterized and their [^1]H NMR spectra reported. The nickel complex of the N2S2 ligand was obtained by reaction with Ni(acac2. The reactivity of the complex was dominated by sulfur as demonstrated by the formation of cationic thioethers by reaction of the nickel dithiolate with alkyl halides including MeI and 1,3-dibromopropane as well as functionalized alkyl halides such as bis(2-iodoethyl)ether and bis(2-iodoethyl)disulfide. The reactivity of the nucleophilic sulfurs was further implicated by the isolation of a sulfinate complex from the reaction of the thiolate with O2 and the formation of heterobimetallic complexes on reaction with electrophilic metal sources such as FeCl2 or Zn(BF(BF4)2,xH2O. X-ray crystallography of the series of complexes demonstrated the wide range of conformations of the ligand. In addition, the metal coordination varied considerably, with nickel assuming 4, 5, and 6 coordination upon modification of the ligand. The iron complex of the N2S2 ligand was prepared in an analogous manner and structurally characterized while the cobalt complex was characterized only by elemental analysis. The electrochemistry of the metal complexes was examined by cyclic voltammetry. Many of the alkylated derivatives of the nickel complexes demonstrated reduction potentials at ca. - 500 mV (vs. Ag°/AgCl). The dimethylated derivative was chemically reduced with Zn° and Cp2Co and the reactivity of the reduced species toward electrophiles examined. Several of the alkylated complexes were reduced with NaBH4 and examined by EPR spectroscopy. Nickel and cobalt complexes of the N2O2 were synthesized by deprotonating the ligand prior to reaction with a metal halide. Characterization was performed by NMR alone as repeated attempts to crystallize the products failed. The reactivity of the cobalt complex with oxidants was compared to the reactivity of the cobalt complex of the diacetate of DACO. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Chemistry." |
| Physical Description: | xiv, 140 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |