Cyanide-Bridged Polynuclear Compounds of Molybdenum(III) and Rhenium(II)
Abstract
Since the discovery of [Mn₁₂O₁₂(CH₃COO)₁₆(H₂O)₄], research in the area of molecular magnetism has been directed at designing single molecule magnets (SMMs) whose slow paramagnetic relaxation occurs with long relaxation times and at relatively high temperatures. Both polynuclear and mononuclear compounds have been studied with respect to the fundamental characteristics required to make SMMs viable options for device applications including memory storage, spintronics, and quantum computing. In recent years much progress has been made with respect to mononuclear magnets but approaches that incorporate knowledge of strong anisotropy in exchange coupled systems are still underexplored. Specifically, anisotropic exchange represents an important option for improving the properties of polynuclear SMMs. Despite growing interest in the topic, lack of numerous examples of such systems have hampered progress in this area. This dissertation describes studies of new molecules and synthetic techniques to systematically study conditions that lead to Ising-type anisotropic exchange in heavier transition element molecules.
By drawing on previous work with the cyanometallate moieties [Moᶦᶦᶦ(CN)₇]⁴⁻ and [(triphos)Reᶦᶦ(CN)₃]⁻ , new precursors and synthetic strategies were developed to aid research in the area of anisotropic exchange interactions. Mo-Ln chains with the formula {K[Ln(tmphen)₂(H₂O)₂Moᶦᶦᶦ(CN)₇]} were characterized structurally and magnetically and revealed that more work could lead to interesting Mo-Ln nanomagnets. A cyanometallate wheel with the formula [Moᶦᶦᶦ(CN)₇]₆[Ni(L)]₁₂∙24H₂O demonstrated that incorporating [Moᶦᶦᶦ(CN)₇]⁴⁻ into known architectures can improve magnetic properties. A new, heteroleptic Moᶦᶦᶦ cyanometallate was isolated that will facilitate synthesis of new molecules. Three new compounds that incorporate Reᶦᶦ and Vᶦᶦ demonstrate the requirements for observing anisotropic exchange with [(triphos)Reᶦᶦ(CN)₃]⁻ . Future work with these strategies will be helpful for investigating the importance of anisotropic exchange as an alternative for the design of single molecule magnets with higher barriers for both the d and f-block elements.
Citation
Kempe, David K. (2019). Cyanide-Bridged Polynuclear Compounds of Molybdenum(III) and Rhenium(II). Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /186328.