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Title: Metal complexes of 1,2 quinone monooximes and their applications in organic synthesis.
Author: Chakrabarti, Jayatibha.
ISNI:       0000 0001 3526 0126
Awarding Body: University of North London
Current Institution: London Metropolitan University
Date of Award: 1995
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Systematic investigations of the reactions of 1,2-quinone monooximes (qoH) with alkali (lithium, sodium and potassium) and alkaline earth metal (magnesium and barium) hydroxides and acetates [M(OH)n or M(OAc)r] have been carried out. In the case of 1,2-naphthaquinone 1-oxime (1-nqoH) and 1,2-naphthaquinone 2-oxime (2- nqoH), all the alkali metals form complexes of types M(qo). nS and M(qo)(qoH)(S) [S = H20 or EtOH]. M(qo). nS arises when a reactant molar ratio [MOH: qoH] of 1: 1 is used whereas M(qo)(qoH)(S) is formed when the ratio is 1: 2 or 1: 3. An analogous behaviour is also observed in the reactions of NaOH and KOH with 5- ethylamino-4-methyl-1,2-benzoquinone 2-oxime (5-Et-4-MeqoH). The reaction of LiOH with 5-Et-4-MeqoH in the ratio of 1: 1 gives Li(go)(qoH)(H20) whereas using molar ratios of 1: 2 and 1: >_ 3 give Li(go)(qoH),. 1' H20. The alkaline earth metals form complexes of type M(go)2.2H20 with 1-nqoH and 5-Et-4-MeqoH. Complexes of type M(Mpo). nS and M(Mpo)(MpoH). S [M = Li, Na, K], M(Mpo)2.2H20 and M(1-Ppo),. 2H; 0 [M = Mg and Ba] result from the reactions of MOH, Ba(OH)2 and Mg(OAc), with 1,3-dimethyl-lH-pyrazole-4,5-dione-4-oxime (MpoH) and 3-methyl- 1-phenyl-lH-pyrazole-4,5-dione-4-oximes (1-PpoH). Structural investigations of the qoH complexes noted above were carried out using spectroscopic, magnetochemical and X-ray crystallographic studies. All the complexes exhibit association as indicated by LSIMS. Their IR spectra indicate the quinone oximic character of the ligands and the involvement of the carbonyl group in the bonding of the ligand to the metal atom. X-ray studies of the lithium and sodium complexes of 5-Et-4-MeqoH show that the ligand chelates to the metal atom through the nitrogen atom of the oxime group and the oxygen atom of the carbonyl group and suggest that its structure can be best described as an intermediate between the quinone oxime and imino oxime form. In the bis-chelates, the metal atom is penta coordinated whereas hexa coordination is shown by Li(go)(qoH)2. IR studies of the complexes ML, [M = Mn, Ni, Cu and Zn; LH = 1-PpoH and MpoH] and their aquo and pyridine adducts indicate that the ligand exists essentially in the oximic form. The lack of reaction between these complexes and triphenylphosphine suggests that the oxygen atom of the NO group is involved in bonding to the metal atom. This feature is confirmed by the X-ray studies of Zn(Mpo)2(H, O)2 and Mn(1-Ppo)2(py)2 which indicate the presence of six-membered chelate rings and octahedral coordination around the metal atom. Magnetic moment determinations of the aquo and pyridine adducts show that the compounds are magnetically dilute and hence monomeric in the solid state. The lowering of magnetic moment observed for anhydrous complexes is accounted for in terms of association. Support for association is also obtained from the LSIM spectra which show dimetallic and trimetallic species in their spectra. The lithium, sodium and barium complexes of 1-ngoH react with dimethyl acetylenedicarboxylate (DMAD) at -75-50° to give the open chain adduct, O-(1', 2'- dicarbomethoxyethenyl)-1,2-naphthaquinone1 -oxime. Open chain adduct formation is also observed in the reactions of pyrazole-4,5-dione-4-oximes or their lithium complexes with DMAD at 0-40°C. At higher temperatures the reactions lead to Schiff Base type condensation products whose formation is accounted mechanistically in terms of the deoxygenation of the oxime group.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Organic chemistry Chemistry, Organic Chemistry, Inorganic