Magnetic Behavior of Heavy Elements and Heterobimetallic Systems

The focus of this dissertation is the study of the magnetic properties of several novel lanthanide and actinide metal complexes, of particular concentration is the use of SQUID magnetochemistry coupled with electron paramagnetic resonance (EPR). Through these techniques, a deeper understanding of the magnetic behavior of the f elements and their structure-property relationships are realized. The novel neptunium selenite compounds presented in Chapter 3 are simple systems in which to probe the magnetic susceptibilities of transuranic compounds and a soft ferromagnetic material with strong temperature independent paramagnetic effects was synthesized. Chapter 4 also concerns neptunium but in this case a comparison between neptunium iodates, which are expected to be nonmagnetic, assuming a formal oxidation state of +5 which yields a singlet ground (S = 1) assuming spin only contributions. The compounds actually display ferromagnetic ordering at approximately 12 K. Of even further interest is the frequency dependence of the magnetic susceptibility which should not be evident in a magnetically ordered system thus signifying the material have spin glass properties or exhibit magnetic frustrations. The focus of Chapter 5 is the correlations between structure and magnetic properties that are correlated in a large family of heterobimetallic compounds containing lanthanides and copper. The tuning of the magnetic properties can be controlled by careful substitution of lanthanide ions. Of particular interest is the magnetic information revealed via electron paramagnetic resonance which may go unnoticed by bulk magnetization techniques. These measurements clarified the magnetic description of the compounds. Chapter 6 highlights several other compounds that were found to be magnetically interesting. Particularly interesting is a uranium ion in the +4 oxidation state that exhibits spin frustration. Furthermore, a large family of lanthanide-transition metal ions with tellurium and sulfate anions, where both the lanthanides and transition metal ions are able to be substituted yielded a large diversity of magnetic properties. Finally, a compound was synthesized that exhibited two crystallographically unique copper atoms which are distinguishable via high field electron paramagnetic resonance and order antiferromagnetically.