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 [Cu<SUB>2</SUB>(hbp)<SUB>4</SUB>] 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 [{Cu<SUB>2</SUB>(fhp)<SUB>4</SUB>}<SUB>2</SUB>]. Addition of methanol to [Cu<SUB>2</SUB>(bhp)<SUB>4</SUB>] results in the formation of a tetranuclear copper complex [Cu<SUB>4</SUB>(bhp)<SUB>4</SUB>(OMe)<SUB>4</SUB>] with pyridone and methoxide bridges. The analogous reaction with [{Cu<SUB>2</SUB>(fhp)<SUB>4</SUB>}<SUB>2</SUB>] affords the polymer [{Cu<SUB>4</SUB>(fhp)<SUB>4</SUB>(OMe)<SUB>4</SUB>}<SUB>n</SUB>] 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, [Cu<SUB>8</SUB>(μ<SUB>4</SUB>-O)<SUB>2</SUB>(xhp)<SUB>8</SUB>(OAc)<SUB>4</SUB>] (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. (<SUP>1</SUP>H) 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 GdCu<SUB>3</SUB> complex with Hchp whereas antiferromagnetic exchange is observed between Gd atoms in a Cu<SUB>2</SUB>Gd<SUB>2</SUB> 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 [Ni<SUB>3</SUB>(chp)<SUB>4</SUB>(R'COO)<SUB>2</SUB>(ROH)<SUB>6</SUB>] (R' = Ph, Me). In contrast extraction with THF gave the metallocycle [Ni<SUB>12</SUB>(xhp)<SUB>12</SUB>(OAc)<SUB>12</SUB>(H<SUB>2</SUB>O)<SUB>6</SUB>(THF)<SUB>6</SUB>] (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 [{Mn<SUB>2</SUB>(chp)<SUB>2</SUB>(OAc)<SUB>2</SUB>(MeOH)<SUB>2</SUB>}<SUB>n</SUB>]. Magnetochemistry shows antiferromagnetic coupling between the Mn(II) centres.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:651725 |
| Date | January 1995 |
| Creators | Grant, Craig MacIan |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/12061 |
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