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Title: Polynuclear nickel and cobalt complexes of substituted pyridone ligands
Author: Brehin, E. K.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1997
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This thesis presents routes to several high nuclearity nickel and cobalt complexes of pyridonate ligands. Solution reactions of simple metal salts and the sodium salts of 6-methyl-6-bromo- and 6-chloro-2-pyridone produced compounds whose nuclearities range from three to twenty four. Among these is [Co24(OH)18(OMe)2(Cl)6(mhp)22], the highest nuclearity complex containing cobalt, which consists of cubic-close packed planes of hydroxide, methoxide and chloride anions bridging cobalt centres. Preliminary magnetic studies indicate the presence of a high spin ground state and the possibility of superparamagnetic behaviour. Thermolysis reactions of protonated pyridones produced the first nickel and cobalt complexes which contain M4O6 adamantane units. They are also the first examples of vertex- and face-sharing adamantanes. Introduction of rigid linking carboxylate ligands to the reactions of 6-methyl-2-pyridone produced a family of deca- to dodecanuclear nickel and cobalt complexes whose structures are based on centred-tricapped-trigonal prisms which contain either zero, one or two additional caps on the 'upper' and 'lower' triangular faces. The nuclearity and structure of these complexes can be controlled through variation of pyridonate, carboxylate and solvent. Similar reactions involving 6-chloro-2-pyridone produced, amongst others, a series of trimers of general formula [M3(O2CR)2(xhp)4(R'OH)6] and a dodecanuclear cobalt metallocycle. Replacement of binucleating with tetranucleating carboxylates led to the synthesis of two large polymetallic complexes : a cobalt tridecamer and a nickel-sodium supracage. The supracage assembly in which four nickel cubanes are linked through a sodium octahedron appears to be unprecedented. The synthetic procedures used to produce homometallic species have been expanded to give a number of bimetallic 3d-3d and 3d-4f complexes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available