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CHEMICAL AND ANTIBACTERIAL STUDIES OF MIXED LIGAND TRANSITION METAL COMPLEXES

Tabassum, Hamida (1994) CHEMICAL AND ANTIBACTERIAL STUDIES OF MIXED LIGAND TRANSITION METAL COMPLEXES. PhD thesis, University of Karachi, Karachi.

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Abstract

The research work comprises of the synthesis, chemical, spectroscopic and antibacterial studies of mixed ligand complex of copper, silver, nickel and cobalt. The ligands used during the course of this research work were monodentate as well as bidentate Triphenyphosphine is the primary ligand and a study on the replacement of triphenylphosphine from various metal triphenylphosphine complexes with ligands like 2-aminopyridine, 2-methylpyridine, 2-aminophenol and p-methoxyaniline (p-anisidine) were made These ligands differ in their chemical properties and in the position of nitrogen atom present in the molecule. It is situated in the ring (methylpyridine), outside the ring (aminophenol, p-anisidine) whilst both in and outside the ring (aminopyridine). Thus the complexes synthesized have different stereochemistry regarding the structure and the number of ligands attached to the metal atom A number of complexes were prepared having MX:L ratio of 1:2, 1:2 and 1:n, where MX is the hole, thiocyanato and nitrato compound of copper, silver, nickel and cobalt triphenylphosphine in dimeric [MX(PPh3)2]2, tetrahedral [MX(PPh3)3]3, and tetrameric [MX(PPh3)3]4, from respectively, and L is the above mentioned organic ligands. No such work has been reported in the literature on these mixed ligand complexes The newly synthesized complexes were repeatedly recrystallized for their purity and then subjected to various physical tests as melting point and solubility in various polar and nonpolar solvents. Spectroscopic studies were carried out for the structural studies of these compounds together with comparison with published data of authentic compounds (wherever possible) The infrared spectra of the compounds showed band intensities for triphenylphosphine as well as the secondary ligands in most of the copper compounds. Very little of silver compounds showed the coordination of both the ligands. In case of nickel and cobalt there was not a single comlex having both the ligands; all these complexes on reaction with the ligand liberated out triphenylphosphine and secondary lignad was substituted completely in some cases In the ultraviolet slpectra no band due to transition of electrons has been observed because of a d10 system of the metal atom and this has been confirmed by magnetic susceptibility measurements of the compounds which showed unit positive oxidation state of the central metal atom. Conductivity measured in nitrobenzene at 25C showed these compounds to be non-ionic in nature. In the visible spectra M—X bonding was studied The variation in stoichiometry and the probable structure of these complexes have been discussed in view of their chemical and spectral data; these complexes have been suggested to have structures like [MX(PPh3)(L)]2, [MX(PPh3)2(L)]2, [MX(PPh3)(L)2]2; [MX(PPh3)2(L)2]2, or [MnXn(PPh3)n(L)n]2, (where n may have values ranging from 2….) the experimental data are in support of the bridging of halides, nitrate or thiocyanante group between the two metal atoms The present study yielded different types of new complexes. The structures proposed for these compounds are based on the information gained from analytical and IR data_Contd.

Item Type:Thesis (PhD)
Uncontrolled Keywords:mixed ligand transition, copper, silver, nickel, cobalt, triphenyphosphine, 2-aminopyridine, 2-methylpyridine, 2-aminophenol. p-methoxyaniline (p-anisidine)
Subjects:Biological & Medical Sciences (c) > Medical Sciences (c2) > Pharmacy(c2.5)
ID Code:1109
Deposited By:Mr. Muhammad Asif
Deposited On:20 Dec 2006
Last Modified:04 Oct 2007 21:04

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