Date of Award
8-1980
Degree Name
Doctor of Philosophy
Department
Chemistry
Abstract
Two series of complexes trans-{Co(LL')EDDA}('+) and trans-{Co(LL')DMEDDA}('+), LL' = Meen, 2-Mepn, udmeen, sdmeen, R-dmepn were prepared. EDDA was reacted with cobalt(II) carbonate and the resulting solution combined with the diamine of choice. For the DMEDDA complexes the ligand DMEDDA was first prepared by adding neutralized chloroacetic acid to sdmeen and precipitating out the ligand as the barium salt. The DMEDDA complexes were prepared by reacting the barium salt first with cobalt(II) sulfate and then with the diamines listed above except udmeen. The DMEDDA complexes with R-pn were also prepared. For both series the oxidation of the Co(II) to Co(III) was accomplished by the addition of hydrogen peroxide to the solution with the diamines.
The ligand R-pn was prepared as a tartrate salt by repeated recrystallizations. The tartrate salt was used to prepare R-sdmepn by forming its carbonate followed by a reduction.
The visible spectra of the complexes was used to ascertain their trans nature.
The NMR data showed that both the tetradentate ligand and the bidentate ligand are fixed in their conformations. The N-methyl groups in these complexes are in their equatorial orientation. During deuteration some of the bidentate ligand seem to change their conformation.
The complexes were resolved using silver salt of D-tartaric acid. The complex trans-{Co(dmeen)DMEDDA}('+) was not obtained in large enough quantity to carry out a resolution. Attempt to resolve the complex trans-{Co(udmeen)EDDA}('+) was unsuccessful. For the resolved complexes, enantiomeric pairs were obtained.
Preparation using the optically active ligand R-pn and R-sdmepn were stereospecific giving isolable (+)(,D) isomer and not the (-)(,D-) isomer.
Absolute configuration to the complexes were assigned by comparing their CD spectra to those of known complexes.
The CD band intensities for the EDDA complexes in both the A(,1g)-A(,2g) and A(,1g)-E(,g) electron transition region showed additivity confirming the hexadecadal rule. For the DMEDDA complexes the results were not as good but these complexes showed qualitative additivity in accordance with the hexadecadal rule.
Access Setting
Dissertation-Open Access
Recommended Citation
Mbah, Godfrey Chinenye, "Stereochemistry and Circular Dichorism of Some Cobalt(III) Complexes with Ethylenediamine-N, N’-Diacetic Acid and N, N'-Dimethylethylenediamine-N ,N'-Diacetic Acid" (1980). Dissertations. 2628.
https://scholarworks.wmich.edu/dissertations/2628