Master of Science
Corrigan, J. F.
The synthesis of heterometallic chalcogenide molecules requires the continued investigation into the appropriate reagents necessary to introduce metal – chalcogen bonds in a controlled fashion. Trimethylsilyl metallochalcogenolates (MESiMe3) act as synthons introducing “ME–“ in solution upon reacting with an appropriate ternary metal reagent, MX (X= halide, acetate, etc.). Recent work makes use of N–heterocyclic carbenes (NHCs) as a class of ancillary ligand that can stabilize these reagents and the heterometallic chalcogenide molecules obtained with them. Building on previous work, this thesis describes the synthesis of group 11 trimethylsilyl metallochalcogenolates stabilized by bis–1,3–tritylimidazole–2–ylidene (abbreviated ITr) to build this library of compounds and investigate their reactivity towards dinuclear chalcogenide molecules, [(ITr)2M(μ2–E)M’] (M=Cu, Ag, Au; E=S, Se). Surprisingly, the reaction of [ITrMESiMe3] with [ITrMOAc] did not yield the desired products in a selective manner. Attempts are made to rationalize the failure to obtain both the homo and heterometallic compounds by this general method and by other previously established techniques.
Summary for Lay Audience
Transition metal chalcogenides are compounds made of a combination of an element from the middle of the periodic table together with one of the chalcogens (oxygen, sulfur, selenium, or tellurium). These solids are found in nature as minerals and ores from which valuable metals can be extracted; however, recent work has shown their suitability for a wide variety of applications ranging from photovoltaic absorbers to catalysts. In engineering the material properties of these compounds further, chemists have learned that controlling the chemical bonding between these elements and forming discrete molecules allows for improved control of their material properties. The challenge of assembling these molecules in a controlled manner is often overcome using other organic molecules, known as ligands, which chemically bond to the metal or chalcogen atoms to effectively control the degree of bonding between these types of elements. The nature of the chemical bond between the ligand and the metal, as well as the ability for this ligand to encompass the metal atom, controls the ability to isolate molecular metal chalcogenides. The work in this field is ongoing, with homometallic (one metal) or heterometallic (two or more metal types) molecules having been made. To continue developing the synthesis of heterometallic chalcogenide molecules, the work in this thesis describes a contribution to the growing library of metal-chalcogen complexes incorporating N-heterocyclic carbenes (NHCs) as effective ligands, and investigating the chemical reactions thought to be able to produce a new class of dinuclear, heterometallic molecules.
Nahhas, Dickron Richard, "N-Heterocyclic Carbene Ligated Group 11 Trimethylsilylchalcogenolates: Building Blocks for Heterometallic Chalcogenide Molecules" (2020). Electronic Thesis and Dissertation Repository. 6985.