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Title: Polymetallic complexes of substituted pyridone ligands
Author: Grant, Craig MacIan
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1995
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The crystal structures of copper(II) pyridonate complexes are reported with the 6-bromo- (Hbhp) and 6-fluoro (Hfhp) derivatives of 2-pyridone. With Hbhp a dinuclear complex results [Cu2(hbp)4] similar to that previously reported for 6-chloro-2-pyridone (Hchp). With Hfhp a tetranuclear copper complex is obtained which consists of a dimer of dimers [{Cu2(fhp)4}2]. Addition of methanol to [Cu2(bhp)4] results in the formation of a tetranuclear copper complex [Cu4(bhp)4(OMe)4] with pyridone and methoxide bridges. The analogous reaction with [{Cu2(fhp)4}2] affords the polymer [{Cu4(fhp)4(OMe)4}n] with a tetranuclear repeat unit. U.V.-vis and E.P.R. spectroscopies were used to investigate the disruption of copper/pyridonate complexes by addition of methanol. Magnetochemistry (5-300 K) of all Cu(II) complexes are discussed and in general reveal antiferromagnetic coupling between Cu(II) centres. The thermolysis reactions of hydrated copper acetate with protonated pyridones gave a range of cotanuclear species, [Cu84-O)2(xhp)8(OAc)4] (x = Cl, Br, Me). Thermal (D.S.C./T.G.A.) studies show initial formation of the homoleptic copper species which reacts further with unreacted copper acetate in solution. N.M.R. (1H) studies show retention of structure in solution. A series of copper/lanthanoid complexes were synthesised by stepwise reaction of copper/pyridonate complex with hydrated lanthanoid nitrates. Structural analysis reveals three types of Cu/Ln complexes with different Cu/Ln ratios. The nature of pyridone substituent, solvent and size of lanthanoid are discussed in relation to structure type. Magnetochemistry reveals weak ferromagnetic coupling between Cu and Gd in a GdCu3 complex with Hchp whereas antiferromagnetic exchange is observed between Gd atoms in a Cu2Gd2 compound with Hfhp. The thermolysis reaction between hydrated nickel acetate and Hchp was investigated by D.S.C./T.G.A. Extraction from the melt product with ROH (R = Me, Et) gave linear trinuclear species of formula [Ni3(chp)4(R'COO)2(ROH)6] (R' = Ph, Me). In contrast extraction with THF gave the metallocycle [Ni12(xhp)12(OAc)12(H2O)6(THF)6] (xhp = chp, bhp). The magnetic properties of both structure types are discussed. The reaction of hydrated manganese(II) acetate with Na(chp) in ethanol afforded the one-dimensional polymer [{Mn2(chp)2(OAc)2(MeOH)2}n]. Magnetochemistry shows antiferromagnetic coupling between the Mn(II) centres.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available