Transition metal complexes with polyamine ligands
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
Tri and pentaaminecobalt (III) complexes of various linear and substituted polyamine ligands have been studies. A series of complexes of the type trans – Co (ABA)X₃ (ABA = tridentate linear polyamic = dien, 2,3-tri, dpt or 4-dodec-dien) have been prepared in an investigation to determine the extent to which ring size influences the stereochemistry of the facultative ligands. The preparation of μ-peroxodicobalt (III) decamine perchlorates, [Co₂(AA)₂(ABA)₂0₂](ClO₄)₄.xH₂O, and their decomposition with HCL/EnCL₂ solution to form isomeric complexes of the form Co(AA)(ABA)Cl²⁺ (AA = bidentate linear polyamine – en, pn, ibn, tmd; ABA = tridentate linear polyamine = dien, 2,3-tri or dpt) has been investigated. The reaction of complexes of the type trans – Co(ABA)X₃ (ABA = tridentate linear polyamine = dien, 2,3-tri or dept) with linear diamines (en, pn, ibn, trad, Me-tmd, Bu-tmd, tmd-hex, Nip-ibn or stein) has also been used as an efficient method of preparing isomeric (Co(AA)(ABA)Cl²⁺ complexes. Using the above and other reaction routes, the following number of isomers (in parenthesis) have been synthesised; Co(en)(dien)Cl²⁺ (3), Co(pn)(dien)Cl²⁺ (7), Co(ibn)(dien)Cl²⁺(7), Co(stein)(dien)Cl²⁺ (4), Co(tmd(dien)Cl²⁺ (7), Co(Me-tmd)(dien)Cl²⁺ (5), Co(Bu-tmd)(dien)Cl²⁺ (2), Co(tmd-hex)(dien)Cl²⁺ (2), Co(Nip-ibn)(dien)Cl²⁺ (5), Co(1,4-bn)(dien)Cl²⁺ (1), Co(2,-tri)(en)Cl²⁺ (2), Co(en)(dpt)Cl²⁺ (2), CO(pn)(dpt)Cl²⁺ (4), Co(ibn)(dpt)Cl²⁺ (4) and Co(tmd)(dpt)Cl²⁺ (6). Various isomeric acidopentaaminecobalt (III) complexes have been derived from the isomeric chloro complexes obtained from the above reactions. All complexes have been characterised by their infrared and visible absorption spectra. In addition, crystallographic space groups and unit cell dimensions of some isomers hav been determined. The crystal structures of the π and K isomers of [Co(en)(dien)Cl]Encl₄ have been determined. For the π isomer, the three nitrogens of the diethylenetriamine ligand are in a facial configuration and the chlorine atom occupies one of the two equivalent cis positions relative to the coordinated secondary amine group of the diethylenetriamine. The ethylenediamine ligand occupies the remaining two coordination positions. For the k isomer, the three nitrogen atoms of the diethylenetriamine ligand are in a plane with one nitrogen atom of the ethylenediamine ligand, while the second ethylenediamine nitrogen atom is trans to the chlorine atom. The orientation about the secondary nitrogen group of the diethylenetriamine ligand is such that the NH proton is remote from the coordinated chlorine atom.