Exploring synthetic strategies towards novel magnetic materials - a structural, magnetic and spectroscopic study

Houton, Edel
This thesis reports the exploration of various synthetic strategies towards the synthesis of novel magnetic materials, which were studied both structurally and spectroscopically. An outline of results chapters is given below. Chapter Two reports the synthesis, structural and magnetic characterization of a pair of model Mn dimers with formulas: [MnIII2ZnII2(Ph-sao)2(Ph-saoH)4(hmp)2] (2.1) (where Ph-saoH2 = (2-hydroxyphenyl)(phenyl)methanone oxime and hmp = 2-hydroxymethylpyridine) and [MnIII2(Naphth-sao)2(Naphth-saoH)2(MeOH)2]·4MeOH (2.2) (where Naphth-saoH2 = 2-hydroxy-1-naphthaldehye oxime) constructed via oxime ligands. These dimers were used as model complexes with which to examine the magneto-structural relationship in oxime-bridged MnIII complexes. In an attempt to examine the effect of sterically demanding oximes and carboxylate co-ligands towards Fe-oxime cage formation, Chapter Three presents the synthesis and magnetic behavior of the hexametallic siblings [FeIII6O2(Naphth-sao)2(O2C-C10H8)10(H2O)2]·8MeCN (3.1) (where ¯O2-C-C10H8 = 1-naphthoate and Naphth-saoH2 = 2-hydroxy-1-naphthaldehye oxime) and [FeIII6O2(Naphth-sao)2(O2C-C14H10)10(H2O)2]·8MeCN (3.2) (where ¯O2C-C14H10 = 9-anthracenecarboxylate and Naphth-saoH2 = 2-hydroxy-1-naphthaldehye oxime), along with the tetranuclear cube-like cage [FeIII4(tert-butyl-sao)4(MeOH)4Cl4] (3.3, constructed using the 3,5-di-tert-butyl salicylaldoxime (tert-butyl-saoH2) ligand). In a similar vein to the work described in Chapter Three, we report in Chapter Four the solvothermal synthesis and structural and magnetic characterisation of a family of discrete CrIII cages (4.1-4.3) and extended network materials (4.4 and 4.5), each comprising trimetallic oxo-centred {CrIII3O(O2CR1)3(R2-sao)3}2- (R1 = H, CH3, C(CH3)3, C14H9; R2 = Me, tBu, Naphth, Ph) units linked via connector Na+ cations. The structural characterisation of a [Cr4] complex (4.6) is also discussed here. The final research chapter (Five) reports on the facile synthesis and D tensor elucidation of a family of Mn(III) monomers using an efficient (5 minute duration) synthetic route. These complexes are: [MnIIIF3(H2O)(L1)] (5.1), [MnIIIF3(H2O)(L2)] (5.2), [MnIIIF3(H2O)(L3)] (5.3), [MnIIIF3(H2O)(L4)] (5.4), [MnIIIF3(H2O)(L5)] (5.5) and [MnIIIF3(H2O)(L6)] (5.6), where L1 = 2,2'-bipyridine, L2 = 1,10-phenanthroline, L3 = 6-methyl-2,2'-dipyridyl, L4 = 4,4'-dimethyl-2,2'-dipyridyl, L5 = 5,5'-dimethyl-2,2'-dipyridyl and L6 = 5-chloro-1,10-phenanthroline.
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Attribution-NonCommercial-NoDerivs 3.0 Ireland