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Polycationic Arene Chromium Tricarbonyl Complexes

Christofi, Anna Maria; (1999) Polycationic Arene Chromium Tricarbonyl Complexes. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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The formation of charged arenes bound to metals may provide materials with interesting electrical properties and such materials may exhibit molecular recognition with specific molecules. Polysubstituted benzyl-alcohols and benzyl-polyols were converted to the corresponding chromium carbonyl complexes. Reactions with PBrs, BBr3 and HBr converted these into the corresponding bromides, which were then treated with DABCO (1,4 diazabicyclo[2.2.2]octane) and N-mono-substituted DABCO derivatives to give polycationic arene chromium complexes. Certain patterns of substitution produced complexes which show restricted rotation. The chromium tricarbonyl unit can be used as a probe for the electron density on the ring, since the carbonyl bands in the infra-red spectrum change in frequency, depending on the electronic effects of the groups on the ring. The more electron-withdrawing the groups, the higher the frequency of the carbonyl bands. By observing these shifts in the carbonyl bands, the counter-ions of the polycationic arene chromium tricarbonyl complexes were shown to interact to a different extent with the polycationic complexes. A model is advanced to account for these observations. The binding strength of these polycationic complexes with various anions in host-guest type chemistry was investigated using the method of NMR titration. Changes in the chemical shift are observed with different concentrations of counter-ions and by varying the concentrations of host and guest it is possible to determine the binding constant and the stoichiometry of binding. A comparison was made between the complexed and uncomplexed systems as hosts with the same guest molecules.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Polycationic Arene Chromium Tricarbonyl Complexes
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
URI: https://discovery.ucl.ac.uk/id/eprint/10122670
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