For metal complexes, racemization studies have been largely confined to those of homochelate type. An extension of such studies to heterochelate complexes might be expected to permit a more detailed understanding of the mechanisms involved, since with these compounds it is possible to produce a systematic change in the number of ligands of one type and also to change.the overall charge on the complex.
This thesis contains the results and conclusions of a study of the racemization reactions of an interrelated series of chromium(III) complexes with the ligands 1,10-phenanthroline, 2,2'-bipyridine, and oxalate. i.e., the series
[Cr ox2 phen]-, [Cr ox2 bipy]-
[Cr ox phen2]+, [Cr ox bipy2]+
[Cr phen3]3+, [Cr bipy3]3+.
The racemization, oxygen exchange, oxalate ligand exchange, and aquation of the tris-oxalato anion [Cr ox3]3- have been thoroughly investigated by previous workers. Similarly, Broomhead has studied in some detail the racemization of the anions [Cr ox2 phen]- and [Cr ox2 bipy]-. However, no information is available on the general reaction behaviour of the remaining cationic complexes.
The racemization results of the present study are supplemented by an investigation of the oxygen exchange reaction between the coordinated oxalate group and solvent water for the complexes [Cr ox2 phen]-, [Cr ox2 bipy]-, [Cr ox phen2]+, [Cr ox bipy2]+, and [Cr ox en2]+. These topics are covered in Chapters 1, 3, 4, and 5, while Chapter 2 is devoted to the preparation, resolution, and characterisation of the cations [Cr ox phen2]+ and [Cr ox bipy2]+ and their cobalt(III) analogues.
The final chapter, Chapter 6, is separate from the main theme of the thesis: It is concerned with the assignment of absolute configuration to optically active complexes containing 1,10-phenanthroline and 2,2'-bipyridine ligands, from an analysis of their circular dichroism and absorption spectra. The chromium(III) complexes of the present work, in conjunction with their cobalt(III) analogues, provide suitable series for such a study.