Anet was the first to isolate a stable sigma bonded organochromium (III) complex.1 This was the benzylpentaquochromium (III) ion obtained by the reduction of benzyl halide with chromium (II) perchlorate. The mechanism of this and similar reactions has been thoroughly studied and is believed to be2,3,4 [see PDF file for formula] where R is an alkyl group and X is a halogen other than fluorine.
All complexes reported in the literature show chromium sigma bonded to an sp3hybridized carbon atom. D. Biggs, of L. Speer's research group, attempted to synthesize a complex containing chromium sigma bonded to an sp2 hybridized carbon atom.5 This was attempted by reacting chromium (II) perchlorate with parabromopyridine in the presence of N,N dimethylformamide (DMF). Amides have been shown in the literature to enhance the reductive power of chromium (II) salts.3,6,7 An orange-brown complex was obtained with Biggs attributed to parapyridylpentaaquochromium (III) ion. An attempt was made to characterized this complex, maily through the infrared (IR) and nuclear magnetic resonance (NMR) spectra of a solid mercury (II) derivative of the complex. Mercury (II) halides have been shown to react with organochromium (III) complexes via bimolecular displacement to yield the corresponding organomercury (II) halide salt which can be precipitated from solution:8,9 [see PDF file for formula]
The IR and NMR spectra of a solid precipitate, obtained after the reaction of mercury (II) nitrate with the orange colored solution described above and subsequent precipitation with chloride ion, led Biggs to believe that he had prepared parapyridylpentaaquochromium (III) ion. Little effort was done to determine the stoichiometry, or the kinetics, of the aquation of the complex. The results presented here are the result of an attempt to establish the stoichiometry and the kinetics of aquation of the reported complex in acidic media. It will be shown that Biggs' assignment of parapyridylpentaaquochromium (III) as the structure of the complex is in error and another structure will be given.
| Identifer | oai:union.ndltd.org:pacific.edu/oai:scholarlycommons.pacific.edu:uop_etds-1447 |
| Date | 01 January 1979 |
| Creators | White, James Dean |
| Publisher | Scholarly Commons |
| Source Sets | University of the Pacific |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | University of the Pacific Theses and Dissertations |
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