Magnetic properties of high-spin metal-cyanide clusters and the directed assembly of a single-molecule magnet

This thesis describes synthetic routes to high-nuclearity metal-cyanide clusters and analysis of the magnetic properties of such molecules. Computer programs developed to analyze magnetic data are also reported.; Chapter 1 provides an overview of strategies and step-wise milestones involved in the creation of single-molecule magnets comprised of cyanide bridged paramagnetic transition metals. The preparation and crystal structure of two metal-cyanide clusters created through non-directed syntheses are reported in Chapter 2. The cluster, [(Me₃tacn)₈Cr₈Ni ₅(CN)₂₄]12+, (Me₃tacn = N,N′,N ″-trimethyl-1,4,7-triazacyclononane), possesses a quasi-face-capped cubic structure. A larger cluster, [(Me₃tacn)Cr₁₀Ni ₉-(CN)₄₂]6+, was obtained by adding excess Na₂[Ni(CN)₄] to a solution of [(Me₃tacn) ₈-Cr₈Ni₅(CN)₂₄]12+. Magnetic data for these molecules are also reported.; Chapter 3 details the crystal structures of metal-cyanide clusters with the highest nuclearities known at the time of publication. The structure of [(Me₃tacn)₁₂Cr₁₂Ni₁₂-CN) ₄₈]12+ features an edge-bridged cube with (Me₃tacn)CrIII units capping four cube faces. Two face-centered cubic units fused through a common vertex comprise the larger [(Me₃tacn)₁₄Cr₁₄Ni₁₃(CN) ₄₈]20+ cluster.; The program Anisofit 2.0 is described in Chapter 4. It was written to model molecules with isolated spin ground states possessing only second order magnetic anisotropy, or zero-field splitting. The design and mathematical detail of the model are explained and the supporting files are defined. The source code is given in Appendix D.; Examples of different metal-cyanide clusters along and interpretation of their magnetic behavior are presented in Chapter 5. This is a tutorial for new students of molecular magnetism. Examples include the trigonal prismatic [(Me₃tacn)₆MnCr₆-(CN)₁₈] 2+ species, [(Me₃tacn)₆(H₂O) ₆Mn₃Cr₆(CN)₁₈]6+, the linear [(Me₃tacn)₂(cyclam)-NiM₂(CN) ₆]2+ (M = CrIII, MoIII) clusters, a zigzag [(Me₃tacn)₂(cyclam)₃(H ₂O)₂Ni₃Mo₂-(CN)₆] 6+ cluster, one-dimensional solids such as {lcub}[(Me₃tacn) ₃MnCr₃(CN)₉]2n+{rcub}_n, and two isomeric forms of {lcub}[(Me₃tacn)(cyclam)NiMo(CN)₃] 2n+{rcub}_n.; The excellent success of the identification of the first cyanide-bridged single-molecule magnet presented has inspired Chapter 6. This Chapter focuses on the magnetic properties of this species and describes methods for single-molecule magnet identification.; The final chapter reports a study of [(Me₃tacn)Mo(CN) ₃], and α- and β-[(Me₃tacn)₂(cyclam)NiMo ₂(CN)₆]I₂ employing high-field, high-frequency electron paramagnetic resonance spectroscopy. The zero-field splitting behavior of these complexes derived through modeling will be described, preceded by additional information pertaining to collection and analysis of such spectra.