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Title: Synthesis and studies of metal complexes of new azamacrocyclic ligands
Author: Omar, Hadi A. A.
ISNI:       0000 0001 3458 8701
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 1987
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The macrocycles referred to in this summary are identified in the frontispiece. Ten new azamacrocyclic ligands have been synthesised and characterised, together with some of the metal complexes they form with the divalent metal ions Ni2+, Cu2+, Zn2+, Pb2+, and Cd2+. The pyridine-containing tetra-azamacrocycle L1, the related N-functionaIised ligands L13 and L17-L19, the penta-azamacrocycles L5-L7, as well as the piperidine-containing tetra-azamacrocycle L4, and the binucleating octa-azamacrocycle L10 were investigated. Diamagnetic square-planar complexes, [Ni(L)] [ClO4]2 (L = L1 and L4), were isolated, and the three isomers formed by L1 were separated and characterised by 13C n.m.r. The structure of unsymmetric [Ni(L)] [ClO4]2 was established by x-ray crystallography. Paramagnetic Ni2+ complexes of L1 were found which were either square-pyramidal [Ni(L1 )X]n+ (X = unidentate ligand; n = 1 or 2), or cis-octahedral [{Ni(L1)}2OX]2+ (OX = oxalate ion) with a tetradentate bridging oxalate group. Structures of the oxalato-complex, and the five-co-ordinate complexes with X = CI− and dimethyl sulphoxide (DMSO), were established by x-ray crystallography. Five- and six-co-ordinate complexes of L5 -L7 were prepared of the type [M(L)]2+ (M = Cu, L = L5 -L7, M - Zn, L = L7, M = Cd, Pb, L = L6-L7) and [M(L)(DMSO)]2+ (M = Ni, L = L6 and L7 , M = Zn, L = L6 ). A crystal structure of [Zn(L7)][ClO4]2 shows that the geometry around the zinc ion is a distorted trigonal bipyramid, with the pyridine N-atom in the trigonal plane, and with a C2 rotation axis passing through the Zn and pyridine N-atoms, and bisecting the C-C bond furthest removed from the pyridine ring. The large ring octa-azamacrocycle L10 forms homobinuclear complexes of the type [M2(L10)]4+ (M = Ni, Cu, Zn), and a heterobinuclear complex [NiCu(L10)]4+ was also separated. Of the complexes formed by the pendent-arm macrocycles L13 and L17-L19, the structures formed by two of them were established by x-ray crystallography. In [Ni(L13)OClO3][CIO4] the Ni2+ ion Is octahedral with co-ordinated perchlorate ion in a trans-position to the co-ordinated pendent-arm, and in [Cu(L19H2)CI]CI the complex is a distorted trigonal bipyramid with only one of the two pendent carboxylate groups co-ordinated, and with the N-atom furthest from the pyridine ring protonated and non-co-ordinating. The ligands and diamagnetic complexes were studied by 1H and 13C n.m.r., and in several cases evidence found for more than one isomer in solution. The Ni2+ and Cu2+ complexes were studied by u.v.-visible spectroscopy, and all of the complexes examined by fast atom bombardment (f. a. b.) mass spectroscopy. Magnetic moments of the paramagnetic complexes were measured at room temperature, and most of the compounds analysed for their elemental composition.
Supervisor: Not available Sponsor: Jāmiʻat al-Fātiḥ
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QD Chemistry