| This dissertation presents EPR spectroscopic, dc magnetic susceptibility, and thermo-magnetic studies of several low-dimensional transition metal systems. This work is primarily focused on the complexes Cu3(O2C16H23) 6 · 1.2C6H12, Ru2(3,5-Cl 4C13H11N2)4Cl · C 6H14, [Ni(hmp)(tBuEtOH)Cl]4, and Cr(C4H 13N3)(O2)2 · H2O, however brief studies of Cr(NH3)3(O2) 2 and [Ni0.1Zn0.9(hmp)(tBuEtOH)Cl]4 are also included to compare with their analogs. Low-dimensional magnetic materials are of current interest due to their variability between quantum and classical magnetism. Chapter 2 describes the powder and single crystal EPR and magnetic susceptibility characterization of the 0-dimensional Cu 3(O2C16H23)6 · 1.2C 6H12 lattice. This complex is shown to be a prototypical spin-frustrated equilateral triangular system with an unusual symmetry lowering effect at very low temperature. Chapter 3 is focused on the 0-d metal-metal bonded complex Ru2(3,5-Cl4C13H11N 2)4Cl · C6H14 that exhibits large zero-field splitting as measured by magnetic susceptibility on oriented single crystals, and butterfly magnetic hysteresis loops, which are analyzed in the context of a phonon bottleneck mechanism. Chapter 4 details the heat capacity characterization of the S = 4 single-molecule magnet Ni(hmp)(tBuEtOH)Cl]4 and its analog [Ni0.1Zn0.9 (hmp)(tBuEtOH)Cl]4. Phase transitions for both complexes are observed and the magnetic contribution of the [Ni(hmp)(tBuEtOH)Cl] 4 is calculated and compared to the experimental data in order to estimate the D-parameter. Chapter 5 presents magnetic susceptibility and heat capacity experiments as a function of temperature over 1.8--300 K and magnetic field 0--9 T on the 2-dimensional antiferromagnet Cr(C 4H13N3)(O2)2 · H 2O and its 3-d analog Cr(NH3)3(O2) 2. The ligand is shown to play a key role in the ordering processes of such systems. The results presented here should provide a significant contribution to the fundamental understanding of unique molecular magnetic phenomena. |
