Chiral Metal Complexes of 1,4,7-Triazacyclononane and Related Ligands

[摘要] The aim of this project was to investigate some metaSl complexes containing the 1,4,7-triazacyclononane moiety, particularly in respect of their optical activity. The species [Co(tacn)2]Cl3.5H2O was investigated and its circular dichroism spectrum decomposed into A2(T1) and E(T1) components. The analogous chromium complex was prepared and was found to spontaneously resolve on crystallisation. Optically active crystals were investigated by absorption, circular dichroism, luminescence and circularly polarised luminescence spectroscopies. The c.p.l. spectra of [Cr(tacn)2]Br3.5H2O represent only the third use of this technique on a crystalline sample. The bulk of the work reported relates to derivatives of tacn with pendant arms such that they constitute N3O3 donors. Two groups of tacn derivatives fulfilling this criterion may be distinguished: those possessing three acetate arms and those possessing three alcohol arms. Of the latter class the ligands thetacn and Methetacn were prepared and their novel metal complexes reported. Particular attention was paid to the cobalt complexes of the chiral ligand 5-Methetacn; an X-ray crystal structure of one form being reported. The acetate ligands tcta and Meteta were used to prepare chiral complexes with various first row transition metals. For all the species involved investigation centred on chiral properties and extensive use was made of circular dichroism and to a lesser extent circularly polarised luminescence spectroscopies, as means of probing the optical activity of metal complexes. On the basis of the optical activity observed in the visible region of the spectra of several first row transition metal complexes, empirical means of determining the absolute configuration of novel MN303 complexes, from their c. d. spectra, are suggested.

[发布机构] University:University of Glasgow

[关键词] Organic chemistry, Physical chemistry