Investigation of Magnetic, Spectroscopic, and Structural Properties of Molecular Metal Compounds

Compounds exhibiting single-molecule magnetism (SMM) are of current interest for potential use in molecular data storage and quantum computing applications. However, rapid magnetic relaxation at desired operating temperatures currently limits the use of these materials, and a more thorough understanding of the magnetic and vibrational transitions that affect magnetic memory is required to inform SMM design. The primary focus of this dissertation is the study of magnetic and vibrational modes in molecular magnetic compounds via advanced spectroscopic techniques such as inelastic neutron scattering (INS), far-IR magneto-spectroscopy (FIRMS), and high-field, high-frequency electron paramagnetic resonance (HFEPR) to directly observe transitions among zero-field split (ZFS) states, spin-phonon couplings, and phonon modes. In many cases, DFT calculations are performed to support the spectroscopic studies. Notably, interesting magnetic interactions are directly revealed, such as the presence of an assembly excitation in meso-tetraphenylporphyrin compounds Fe(TPP)Cl and Mn(TPP)Cl (TPP^2- = meso-tetraphenylporphyrinate, Chapter II) and spin-phonon couplings in Co(PPh₃)₂X₂ (X = Cl, Br, I; Chapter III) compounds. In addition, structural and magnetic properties of Mn(TPP)Br, Mn(TPP)I (Chapter IV), and Fe(TPP)X (X = F, Cl, Br, I; Chapter V) are investigated. These studies aim to provide a more thorough understanding of magnetic transitions in transition metal compounds in order to inform SMM design criteria and reveal potential routes of magnetic relaxation.